CT - 21 - 0408 CT - 21 - 0408 , nicknamed " Echo , " as he was known for " echoing " the standard rules and procedures established for clones , was a clone trooper who served in the Grand Army of the Republic during the Clone Wars . Early in his career , Echo lived within Tipoca City , the capital city of the planet Kamino , and trained in its military complex . As a clone cadet , Echo was part of the squad Domino Squad , overseen by the Siniteen bounty hunter Bric . Echo stayed with Domino Squad until the unit passed their final test ; the completion of the test allowed the members of Domino Squad to become battle - ready clone troopers . For his first off - world assignment , Echo stood guard at Rishi Station , a listening post located on the moon of Rishi , where he and other rookie clone troopers were stationed . When the Confederate General Grievous implemented an attack on the Rishi Station to capture it before proceeding to Kamino . His plan , however , was thwarted by Echo , fellow troopers Fives , Hevy , and clone officers Cody and Rex . Echo , along with Fives , were rewarded with medals for their service on the Rishi moon and were inducted into the 501st Legion . Several months later , both Echo and Fives returned to Kamino , and the two were present when Grievous , along with Dark Acolyte Asajj Ventress , initiated their attack on Tipoca City . Following the retreat of Grievous and Ventress , which ended the battle , Echo and Fives were once again given accolades for their bravery and efforts , and became ARC troopers . Echo later participated in the rescuing of Jedi Master Even Piell , who was captured by Confederate forces and taken to the Citadel . Echo and his group — lead by Jedi Generals Obi - Wan Kenobi and Anakin Skywalker — found Piell in the prison , and , as they tried to escape with the Jedi Master , were stopped by the facility ' s warden , Osi Sobeck , and his battle droid force . As Echo and his team looked for an escape route that would lead them back to their shuttle outside of the Confederate prison , more of Sobeck ' s security droid forces attacked them . They found their shuttle , although it was being watched by stationed commando droids on various towers around the shuttle ' s landing platform . When a commando droid began to fire at the shuttle with a laser cannon , Echo tried to stop the droid . Yet , instead , the droid killed Echo , as well as destroying the shuttle in the process . Biography . Training with Domino squad . CT - 21 - 0408 was a clone trooper who served in the Grand Army of the Republic during the Clone Wars . Around 21 BBY , CT - 21 - 0408 was assigned to Domino Squad , a unit of clone cadets . Because CT - 21 - 0408 often " echoed " the rules and procedures clone troopers had to follow , the other Domino Squad clone cadets — Cutup , Hevy , Fives , Droidbait — nicknamed him " Echo . " Echo and Domino Squad lived on the planet Kamino ’ s capital Tipoca City , and trained in its military complex . Overseen by Siniteen Sergeant Bric — a bounty hunter himself — Echo and Domino Squad engaged in combat simulations , which placed them head - to - head with battle droids . For their simulation battles , each clone cadet , including Echo , used non - lethal weapons so no clone could be injured during one of their simulations . Furthermore , all clone cadet squad members had to work as a team to successfully pass the simulation . For Domino Squad , however , the team rarely got along with each other . During a practice exam , fellow Domino Squad member Hevy broke away from the struggling group , while Echo , Fives , Droidbait , and Cutup remained behind barricades . As the simulation test progressed , the group of individuals that were watching Domino Squad ' s simulation — Bric , Arcona El - Les , and Jedi Master Shaak Ti — took concern of Domino Squad ' s recklessness . Bric expressed the group ' s inability to work as a team , and wanted to send them to Tipoca City ' s maintenance crew , where rejected clones went . Ti noticed Echo ' s inability to adapt himself into any situation , since he was trying to enforce proper procedures to his teammates . Because the members of Domino Squad could not work together , they failed the test . Afterward , Echo and Domino Squad left the combat room and headed back to the complex ' s sleeping quarters . There , Echo told his squad that they should follow orders and not mess around . While the other Domino Squad members mocked Echo ' s words , Hevy did not enjoy their conversation . When he said that he thought " like an ARC trooper , " Echo questioned him , which angered Hevy . Their heated debate turned into a fight , but the brawl was broken up by the immediate arrival of Bric . While Echo quickly apologized to Bric , Hevy dismissed the sergeant . Bric wanted his team to cooperate with each other , and , if they remain the same , they were a waste of his time . Sometime later Bric and El - Les rallied Domino Squad , as well as other clone cadet squads , for a meeting outside the military complex . Clone Commander Colt , an ARC trooper himself , was to watch the clone cadet ' s final combat simulator test . If a squad past the test , the troopers within the squad would become a combat - ready clone trooper . Colt took interest within Bravo Squad , a unit of clone cadets that past certain tests in " ARC trooper time . " Echo tried to inform his team that they could learn something from Bravo Squad ; however , they negatively ignored him . Echo and Domino Squad followed Bravo Squad to the combat simulator room , and soon watched as Bravo Squad effectively worked as a team during their combat simulation test . Not long after , a cadet from Bravo Squad lifted a pole on top of a citadel in the simulator room which completed the simulation test . With the completion of Bravo Squad ' s test , Echo and Domino Squad entered the combat room . Echo and the rest of Domino Squad past the cadets from Bravo Squad , who teased them by saying " time to watch the Dominoes fall . " However , once the simulator began , Echo and Domino Squad quickly completed certain parts of the simulation faster than their usual rate . As Echo , Fives , Droidbait and Cutup took cover , Hevy , who was destroying droids with his Z - 6 rotary blaster cannon , was clearing a path for them . When Droidbait broke away from the group , however , a droid shot him in the back . Echo noticed this and and yelled for Hevy , although Hevy told him to leave Droidbait alone , as he wanted the squad to head for the room ' s citadel , where the pole to complete the test was located . Because Echo and the other Domino Squad members left Droidbait behind , they automatically failed the test . Colt and El - Les confronted the group and told them they should not leave a man behind . After failing the test , the clone cadets departed back to their sleeping quarters . For Echo and Fives , however , the two clone cadets felt they did not belong within the struggling Domino Squad . Wanting to transfer to a different clone cadet squad , Echo and Fives went to Jedi Master Shaak Ti . Yet , when Echo and Fives requested they should be moved to Bravo Squad , Ti denied their request and revealed that she had faith within Domino Squad . Because of her confidence within Domino Squad , Ti allowed Domino Squad to retake the test . The following day , Ti joined Bric , El - les , and Colt , while Echo and the rest of Domino Squad entered the simulation room . Making similar progress as the day before , albeit not leaving a man behind , Domino Squad reached the bottom of the citadel . However , they noticed that their ascension cables in their belts were missing which were needed to climb the citadel ' s tower . Despite the setback , the clones improvised and decided to climb blaster turrets that acceded up toward the citadel ' s roof . Once Hevy successfully climbed the turrets and lifted the pole on top of the citadel , Domino Squad finally completing the test . Shaak Ti and El - Les spoke positively about their efforts , and due to them working as a team and completing their final test , Echo and the rest of Domino Squad were allowed to become clone troopers . They each received their own medals , as a symbol for their graduation from clone cadet . Rishi moon battle . After becoming a battle - ready clone trooper , Echo , and former Domino Squad members , were assigned their first off - world mission . Echo was stationed at a listening post located on a moon of the planet Rishi , under the command of Sergeant O ' Niner . Along with fellow troopers Fives , Hevy , Droidbait , Nub , and CT - 327 , Echo maintained the listening post to warn the Galactic Republic of any impending Confederate attacks on the nearby Kamino . At one point , when Echo joined the other stationed rookie troopers in the control room of the listening post , Sergeant O ' Niner entered the room and alerted the clone troopers of a routine inspection that would soon commence . Unbeknownst to the group of clone troopers , however , the Confederate General Grievous planned to attack Kamino in order to end the Republic ' s production of clone troopers . Grievous knew that if he attacked Kamino , the Rishi moon listening post would detect the attack , and the stationed clone troopers in the listening post would turn off the base ' s " all - clear " signal , which would alert the nearby Republic fleet . Grievous therefore deployed BX - series droid commandos in " Droch " - class boarding ships to take over the listening post . Meanwhile , a clone trooper raised the listening post ' s shield to protect the base against what appeared to be an approaching meteor shower , which was actually a group of " Droch " - class boarding ships . The droids soon left their transports and began their attack on the Republic base . After three commando droids shot and killed O ' Niner and three other clones , the remaining clone troopers — Echo , Hevy , Fives , and Cutup — evacuated the command center by exiting through a ventilation shaft , which led them outside the listening post . Leaving the ventilation shaft , the four troopers were disheartened when a Rishi eel attacked and devoured Cutup , leaving only Echo , Hevy , and Fives to defend themselves . Eventually , the remaining rookie clone troopers sighted the " Obex " , a " Nu " - class attack shuttle flown by Commander Cody and Captain Rex . The clone officers had arrived for the inspection of the listening post and were unaware of the droid attack . After the two clone officers were attacked by the invading droids , they escaped and met with Echo and the other rookie troops . Having encountered a droid commando disguised in clone armor during their skirmish with the droids , Rex demanded that the rookies remove their helmets to verify that they were indeed clones . After the three rookie troopers obeyed and removed their protective headgear , another Rishi moon eel attacked them . This time , Rex used his DC - 17 hand blaster to kill it with one shot to the eye , a feat that impressed the rookies . When talking with the rookie troopers , Rex dubbed them " shinies , " a derogatory term referring to the troopers ' spotless armor that had not yet seen action in battle . Rex and Cody gave Echo and the other rookie troops their DC - 15S carbines , and Rex suggested a plan to retake the listening post . The group of clone troopers hid near the entrance of the base while Rex impersonated commando droid unit 26 by using the droid ' s decapitated head . The clone captain successfully tricked Units 07 , 08 , and 09 to open the listening post ' s main door , allowing Echo and the clone troopers to ambush the remainder of the commando droids inside the base . Upon entering the command center , the clones defeated the droid units , including their vibroblade - wielding leader . However , their victory was cut short when the clone troopers noticed that General Grievous ' s fleet had arrived above the moon . Due to the lack of response from the commando droids , Grievous sent more battle droids to the listening post . The clones , inside the command center of the listening post , were unable to turn off the " all clear " signal because the droids had hot - wired it . Soon , a droid landing craft descended through the moon ' s atmosphere and landed at the listening post . With the battle droid reinforcements outnumbering the clone troopers , Rex — to the surprise of the rookie troops — ordered the complete destruction of the base . When a confused Echo told the clone captain that the clones ' duty was to protect the base , Rex dismissed him , stating that if the base was destroyed , it would turn off the all - clear signal and alert the nearby Republic fleet of the impending Separatist invasion . To destroy the base , Echo offered the use of highly explosive liquid tibanna , which was used as a fuel source at the station when the Rishi moon entered its freezing cycle . While Rex and Echo went to retrieve the plunk droids that stored the liquid tibanna , Cody , Hevy , and Fives grabbed weaponry from the listening post ' s supply room . With their new supply of weaponry , the clones attacked the invading battle droid forces , buying time for Rex and Echo to wire the three plunk droids together . Unexpectedly to the clones , however , the remote activator to detonate the tibanna inside the plunk droids did not function properly . Hevy offered to stay behind and correct the problem before joining the other clones as they fled the listening post through a nearby ventilation shaft . Once outside , Rex found — to his surprise — that Hevy hadn ' t yet evacuated the listening post . The clone captain contacted Hevy via comlink , but Hevy refused to evacuate the listening post until he was able to repair the detonator . Unwilling to accept Hevy ' s decision , the clones ran to rescue the rookie trooper . Before they could reenter the facility , however , Hevy manually detonated the explosives . The listening post exploded , killing Hevy and all of the droid forces inside . Shortly thereafter , Rex , Cody , Echo , and Fives were picked up by an LAAT / i gunship that carried them off the moon . On board the " Venator " - class Star Destroyer " Resolute " , Jedi Generals Obi - Wan Kenobi and Anakin Skywalker awarded Echo and Fives medals for their service . Following the presentation of the medals , Rex inducted the two clones into the 501st Legion for their part in helping the Republic to thwart the Separatist attack . Defense of Kamino . Several months after the destruction of the Rishi Station , Republic intelligence concluded that the Confederacy was about to invade Kamino . With Kenobi , Skywalker , Rex , and Cody , Echo and Fives departed to Kamino to prepare the defense of the planet . While Kenobi and Skywalker met with Shaak Ti and Kamino Prime Minister Lama Su , Echo and Fives roamed through Tipoca City ' s military complex . After reminiscing about their time as clone cadets in the city , the two soon spotted their old clone trooper friend , 99 , who was carrying a bundle of DC - 15 blaster rifles . 99 was glad to see Echo and Fives , but questioned where was Hevy . When Echo and Fives told him he had given his life to save them on the Rishi moon , 99 sadly showed the two Hevy ' s medal , and told them that Hevy had given it to him . Changing subjects , Echo told 99 about the suspected Confederate invasion of Kamino , and 99 asked the clone if he could help them in any way . With Echo and Five ' s approval , 99 departed to the facility ' s weaponry room to gather weapons for the clone troopers , while Echo and Fives met with an ARC trooper in a docking bay . The ARC trooper gave both 501st Legion clones a dangerous assignment — he wanted Echo and Fives to go outside on a platform bridge and " stay in a sniping position . " Echo and Fives complied and left for the bridge . Once there , the two clones situated themselves , prepared their DC - 15 carbine blasters , and waited for battle to begin . When the invasion began , " Trident " ships , led by the Confederate General Grievous and Dark Jedi Asajj Ventress , climbed the outside structures of Tipoca City . As the ships caused structural damage to the buildings , due to their drills , battalions of B1 battle droids and Aqua droids exchanged fire with stationed clone troopers . On the bridge , Echo and Fives utilized their carbine blasters to shoot down the nearby droids . After 99 visited the two clones and resupplied them with ammo and thermal detonators , battle droids stormed the area , although they were destroyed when Echo tossed a detonator at them . Not long after , a squad of clone cadets approached Echo , Fives , and 99 . When the squad told the clone troopers that they separated from their clone cadet group , 99 offered to bring them back to the city ' s sleeping barracks . Both Echo and Fives departed the platform bridge with 99 and the clone cadets and headed for the indoor barracks . Once there , Clone Commander Cody and Captain Rex joined the group , and told them everyone in the room needed to fight off the droids . The clone cadets , however , disagreed , due to their training being inadequate . Echo tried to boost the clone cadets ' confidence by saying since Kamino was their home , they should defend it . 99 entered the conversation by telling the clones that he knew where the complex ' s armory room was , and if the clones could gather enough supplies , they would be able to hold off the droids . With the decision made , 99 gathered the supplies , and each of the clones equipped themselves with a firearm . Echo and the clones stood behind a door , which led to a sleeping barrack room , and waited for any droid to walk by . Nearby , Grievous led a group of droids down the same hallway the clones where in . After the cyborg General ordered the droids to open the doors , a droid opened the clones ' door , which revealed them . Echo and the clones began to fire at the droids , and lured them inside the barrack room . The clones took defensive positions behind crates as the droids continued their pursuit . As the firefight intensified , 99 tossed thermal detonators to Echo , Cody , and Rex for more firepower . Soon , however , the clones around the crates were being overwhelmed by the droids . Rex used his comlink to alert the clone cadets , whom were hidden inside sleeping bunkers , to reveal themselves to the droids . As they began to fire at the droids , Echo and the others continued as well . However , 99 noticed that the clones ran out of thermal detonators . Despite being told not to retrieve more by Rex , since it was too dangerous , 99 ignored the order and ran toward a nearby door . Yet , battle droids noticed the fleeing 99 , and fired at him , killing him instantly . Despite witnessing 99 ' s death , Echo and the remaining clones destroyed the remainder of Grievous ' droids . Echo and the clones gathered around Fives , who was cradling 99 ' s body on the floor , and mourned 99 ' s loss . After Grievous and Ventress escaped Kamino , which ended the invasion , resulting in a Republic victory , Echo and Fives joined Cody and Rex inside a docking bay . Because of their accomplishments during the invasion , both Cody and Rex were proud of Echo and Fives . The two 501st Legion clone troopers were then allowed to become ARC troopers . Rescuing Even Piell . While serving under Skywalker and Kenobi , Echo and Fives took part in the rescuing of Jedi Master Even Piell , who had been captured by the Confederacy , which wished to extract information about the secret Nexus Route hyperlane that the Jedi Master possessed . In the Jedi Temple on Coruscant , Echo and Fives joined Skywalker , Kenobi , Jedi Master Plo Koon , Cody , and Rex during a meeting around a holograph ic table . As they orchestrated their plan , the team knew that any attack on the facility which contained the captive Piell — a well - guarded Confederate prison known as the Citadel — would be rendered useless due to its security . Skywalker devised a plan of encasing Echo and the team in carbonite in order to avoid detection , as the facility ' s security utilized life - form scanners ; then his astromech droid , R2 - D2 , along with a group of reprogrammed B1 battle droids would fly the carbonite blocks to the Citadel . After the meeting , Echo and the team departed to the Temple ' s hangar bay , where a carbon - freezing chamber , maintained by Ugnaughts , was located . Having doubts of Skywalker ' s plan , Fives , with Echo next to him , told Cody and Rex his worries of entrusting their lives to the droids . Yet , Cody agreed with Skywalker ' s plan , as droids would not be detected . Once Echo and the team were encased in separate carbonite blocks , and stored in a Class Type B escort shuttle , a variant of the " Sheathipede " - class transport shuttle , R2 and the battle droids flew the shuttle to the Citadel , located on the planet Lola Sayu . After passing the prison ' s life - form scan check , R2 - D2 and the battle droids landed the shuttle near a cliff by the Citadel . R2 - D2 released Skywalker and Kenobi ' s team from their carbonite blocks and the team regrouped . Leaving R2 , the battle droids , and the shuttle behind , Skywalker led Echo and the team closer to the cliff ' s edge . Noticing they cannot utilize ascension cables to ascend to the top of the cliff , due to Electro - mine s — which , if touched , would electrocute the object and sound an alarm within the prison — planted throughout the cliff ' s side , Skywalker and Kenobi told Echo and the rest of the team that they would have to free - climb the cliff . Near the top of the cliff , the team noticed a doorway that led into the Citadel itself was ray shielded , Skywalker ' s Padawan Ahsoka Tano entered the Citadel through a nearby ventilation shaft , and she deactivated the ray shield to allow Echo and the team to enter . Next to the doorway , Fives was helping Rex and another clone , Charger , reach the top of the cliff . However , when Charger grabbed Fives ' hand , he slipped and free - fell down toward an Electro - mine , which killed him , and sounded an alarm within the Citadel . Despite alerting the Citadel of their presence , Echo and the team proceeded into the prison anyway . After entering one of the Citadel ' s detention area hallways , the team found out that the walls surrounding the team contained hidden blaster turrets . Once the turrets revealed themselves to the group , the Jedi utilized their lightsabers to deflect the blaster fire , while Echo and the clones fired at the turrets . The turrets were not the only trap the hallway contained , however ; Longshot witnessed an electricity field that was approaching from the distance . While Echo and the others evaded the field , Longshot was not so lucky , as he was instantly killed after being hit by the electric field . The team continued on and found Piell inside a holding cell , and released him from captivity . Though they rescued Piell , the Jedi Master wanted to find his officers , who had also been taken captive by the Confederacy , as one of Piell ' s officers , Captain Wilhuff Tarkin , held in his memory half of coordinates of the Nexus Route ; Piell was in possession of the other half . Piell and Tarkin had memorized the coordinates so that they would not fall to the Confederacy . Still within one of the Citadel ' s detention hallways , Echo and the team were confronted by a group of commando droids , released by the prison ' s warden , Osi Sobeck . A firefight erupted , and the Republic team destroyed the first wave of droids . Sobeck , who was watching the fight via the prison ' s security camera system , released more droids and activated the hallway ' s magnetized ceiling , which took Echo ' s blaster , as well as the other team member ' s weapons — and Skywalker , due to him having a prosthetic hand — albeit leaving the commando droids ' weaponry intact . The clones tried to attack the droids with bare hands , while Kenobi , Tano and Piell used the Force , but neither tactic worked , due to the droids being magnetized to the floor . Skywalker , however , disabled the magnetized ceiling , which allowed his team to reequip themselves and finish off the droids . They soon located and freed Piell ' s men — Tarkin and several clone officers — from a holding cell . Believing that they might run into more trouble with Osbeck ' s prison guards , Kenobi decided the team should split up ; Piell , half of his men , and Cody would go with Kenobi to create a diversion , while Echo , Fives , Rex , Skywalker , Tano , while Piell ' s other officers , including Tarkin , stay together and find an escape route that would lead them out of the prison . That way , if one squad was to be captured , the enemy would only have half the information . As Kenobi ' s team detonated a series of explosives in one of the corridors , Skywalker cut his way through the wall to an old tunnel — of which the strike team knew thanks to some old archive data on the Citadel — Echo and Fives resealed the entrance and continued onward through the tunnels . Skywalker , having contacted R2 to land the shuttle near their location , led his group through the tunnels . When they reached a dead - end , they were ambushed by several commando droids , which were armed with energy shields . Without warning , Tano tossed a few thermal detonators under the droids ' feet , which destroyed them . After Tano used more explosives to blow their way through the rock , Echo and the others proceeded toward a nearby pipeline . Using the pipeline as a way to find an escape route that would lead them toward their landed shuttle , Echo and the team soon reached an exit point of the pipeline . However , outside of the exit hatch , a battalion of battle and crab droids ambushed them . The group escaped , and Skywalker tossed a grenade into the fuel line , and the resulting explosion destroyed the droids . Skywalker ' s team went to Kenobi ' s position , finding the Jedi Master and his men pinned down by droids that were guarding the shuttle . Echo and Fives joined the battle , as more and more droids arrived . When a commando droid , who was stationed on top of a watch tower , began to fire at their shuttle with a laser cannon , Echo reported this to Skywalker . Skywalker and Piell swooped in to attack on a commandeered STAP , but were knocked out . Determined to protect the shuttle , Echo picked up a fallen commando droid ' s shield to defend himself , and attempted to reach the shuttle . However , the droid destroyed the Republic team ' s shuttle , killing Echo in the process . Despite this , the Republic strike team was successfully evacuated by Masters Koon , Adi Gallia , and Saesee Tiin , who were leading a Republic fleet . However , Piell died before the rescue forces arrived , but he passed his knowledge of the Nexus Route to Tano . Personality and traits . When Echo was a rookie clone trooper , Echo had an eye for detail . While stationed at Rishi Station , the trooper was not troubled by the lack of excitement . During his time in Domino Squad on Kamino , Jedi Master Shaak Ti noticed that Echo had trouble adapting to any situation . Instead of helping his fellow troopers in battle , he was constantly telling his Domino Squad members that they were disobeying orders . As a result of him " echoing " the rules and orders the clones had to follow , the troops within his squad gave him the nickname , " Echo , " which would stay with him even after becoming a clone trooper . While stationed on Rishi Station , Echo told the other stationed rookie clones that he enjoyed quiet situations , which gave him time to catch up on the regulatory manuals . Instead of fighting , Echo preferred to be away from the front lines . Despite this , Echo often read manuals to improve his skills he would need as a soldier fighting for the Republic . After evacuating the listening post when it was taken over by Confederate battle droids , Echo was able to inform the other clone troopers on what the manual dictated for situations without a commanding officer . Echo ' s service to the Republic earned him a spot within the Republic ' s 501st Legion . When the Confederacy invaded Kamino , Echo , who now served in the 501st Legion for several months , did not disobey Clone Commander Colt ' s dangerous assignment of guarding a bridge . Along with Fives , Echo tried to boost several clone cadets ' confidence , when they stressed about their training being inadequate for a fight . Because of his accomplishments on Kamino that day , as well as his service within the Grand Army , Clone Commander Cody and Captain Rex allowed Echo to become an ARC trooper . Believing that the shuttle was their only means to escape from Lola Sayu , Echo was determined to protect it at all costs , sacrificing his life , but still failing in his mission . Equipment . When Echo was a clone cadet , his armor was sleek white , but his arm and leg armor featured green markings . On his chest and left shoulder armor , a " 3 " marking was painted on . Echo ' s rookie armor was sleek white as well , and had no dust or damage from fighting because of his lack of combat prior to the Rishi moon battle . After Rex killed the attacking Rishi eel , the clone captain used his hand to stamp some of the eel ' s blood onto Echo ' s chest armor . When Echo became a 501st Legion member , Echo ' s armor featured the Legion ' s distinctive blue markings . Echo had a patch on the left side of his legging armor that read " For Hevy , " which was written in Aurebesh . Echo ' s helmet featured red macrobinoculars . After becoming an ARC trooper , Echo switched to ARC trooper armor , which was equipped with a rangefinder . Behind the scenes . Echo was first featured in " Rookies , " the fifth episode in the of the , which aired on October 24 , 2008 . Like all clone troopers throughout the series , he was voiced by Dee Bradley Baker . In the premiere of " Rookies , " Echo exclaimed the word " hell " once ; however , this word was removed in later broadcasts of the episode . " The Complete Star Wars Encyclopedia " later gave Echo a short entry , and " " gave Echo the clone designation " CT - 26 - 1409 . " However , Echo was later identified as " CT - 21 - 0408 " in the " " . Echo later appeared in the episodes " Clone Cadets " and " ARC Troopers " of the of the " The Clone Wars " , which aired on September 17 , 2010 . The character was also featured in the season three episodes " The Citadel , " which aired on February 18 , 2011 ; and " Counterattack , " which aired on March 4 , 2011 . Echo appears in the non - canon video game , " " , which was released in the United States on March 22 , 2011 and adapted the events of " Rookies " in a humorous way . In March 2014 , following the release of the of " The Clone Wars " , Supervising Director Dave Filoni mentioned that Echo survived the events of " Counterattack . " According to Series Writer Brent Friedman , the character was to be featured in an arc that he wrote focusing on a team of experimental clone commando s called " The Bad Batch , " with the story ' s " emotional hook " being Echo ' s relationship with Captain Rex . The arc would have premiered the series ' seventh season had it been produced , and was later featured on StarWars . com after the Expanded Universe was declared non - canon .