Sentinel ( creature ) The Sentinel , was the name given to the creature that protected an underground city on the planet Alashan . The creature was the byproduct of an ancient complex within the city . The power of the complex caused the creature ' s presence to give off an extremely large energy signal that could be detected at a distance , even by the sensors on an astromech droid . The creature and the complex had been seemingly created by an ancient civilization native to Alashan , whose technology and culture had been lost to time . For some unknown reason , they had sealed their city ' s walls with a massive metal barrier , locking the Sentinel and their ancient technology away from outsiders . The Sentinel possessed near - supernatural powers and strength . Among its arsenal was the ability to fire a concentrated superlaser , as well as the ability to modify its size and to teleport . After being released from its prison by curious Rebel archaeologists , the Sentinel began to slaughter what it perceived as unwelcome intruders . Eventually , due to efforts of Rebels Luke Skywalker and Leia Organa and Imperials Wil ' m Grau and Anarine , the ancient complex was smashed into disrepair , apparently killing the seemingly invincible monster . Biography . Origins . Sometime before the formation of the Republic , a culture of technologically sophisticated beings from the planet Alashan developed a power source with the ability to destroy foreign objects a hundred thousand kilometers from their planet ' s surface . Any record of the source of the power was kept with hieroglyphic writings that adorned the culture ' s massive underground city . To protect the huge metropolis , the Alashans created a complex called the control center . The complex became the source behind the powerful energy that was known as the Sentinel creature . With power to protect the city , as well as the ability to leave the area to attack potential intruders , the Sentinel was a formidable protector of the massive capital . Along with the power to operate a destructive superlaser , the Sentinel could teleport to any place in the city , as well as modify its shape to either fill a doorway or fit itself into small spaces . When the Rebels first entered the massive structure , they found it deathly silent , and compared it to a tomb of sorts . The city was buried five kilometers under the ground and sealed with a large metal door , and the Sentinel creature was locked within the confines of its home , unable to leave . First encounter . Sometime around 0 ABY , Rebel archaeologists arrived on Alashan , believing it to be a dead world and hoping to find technology that could aid the fight against the Galactic Empire — rumors of the ancient Alashan civilization had survived through the years , and the Rebels decided to follow up on those rumors . Sonic scans from the archaeologists revealed a huge underground city within the dead soil of the world . Digging down five kilometers , the archaeologists found a huge metal barrier . Knowing what untold riches the place could hold , the archaeologists broke through the wall , not knowing what it held behind it . In the following time , the Sentinel was freed from his prison and began to seek out the intruders to Alashan . The monstrous creature hunted down the entire team and slaughtered them one by one , leaving their dismantled bodies lying inside the structures they had erected . After missing three routine communications , Rebel scouts were sent to the archaeological station to check on the Rebel team . Scouts Arlo Tyre and Wadie Firestone came upon the destroyed site , discovering the slaughtered archaeologists and their habitat domes broken apart from the inside out . As Wadie checked his sensors , he found an immense energy field inside the main habitat dome . Arlo Tyre approached the dome with practiced caution , but as soon as he found himself in front of the entrance , a concentrated blast of energy from the Sentinel creature ripped through his body , killing him . Seeing that his partner was surely dead , Firestone rushed back to his Y - wing , hoping to escape the powerful force . Unfortunately , as soon as he got his ship off the ground , the Sentinel released another blast of energy , destroying the ship and keeping his appearance unknown for the time being . Second encounter . The Sentinel continued to remain close to the city until it sensed two ships entering the atmosphere of Alashan . The first was the " Staraker " , a ship with experimental shields and speed that had been stolen from the Imperials by a team made up of Luke Skywalker , Leia Organa , and Mici Shabandar . The other was an Imperial cruiser intent on capturing the " Staraker " . The Sentinel fired a blast into space with deadly accuracy , destroying the Imperial cruiser . As the " Staraker " dived desperately , the Sentinel fired another blast at the ship , but the experimental ship ' s special shields were able to deflect some of the blast , keeping it from being totally destroyed . However , the ship was critically damaged and plummeted to the planet ' s surface . Additionally , it seemed that several of the Imperials had survived their cruiser ' s destruction by evacuating in escape pods , and the Sentinel resolved to hunt down all of the intruders . Pinpointing the crash of the Rebel ship in a section of hardened lava , the Sentinel blasted away the hardened lava to get to the damaged ship . Crawling into the " Staraker " , the creature found Mici , but she rendered no life signals , and it tossed her aside , leaving the ship alone . The beast rushed back to its home , finding that the intruders had already entered the city . The Sentinel killed Eger Djambo , a stormtrooper placed as a sentry outside the entrance , and reentered its home . The beast immediately found another stormtrooper , Voss , and ripped through his armor , throwing him from one of the city ' s high towers . The Sentinel then pinpointed the main group and advanced upon them . However , concentrated blaster fire from the group collapsed the tunnel on top of the creature , stalling it temporarily . Hunt . Unfortunately for the Rebels , the Sentinel proved almost invincible and survived the landslide . Sneaking throughout the base , the creature tried to sneak up on the intruders one by one . The Sentinel was able to sneak up on Leia Organa , but just as it made to jump upon her , Luke Skywalker swung down and pulled her from the creature ' s grasp . With his prey swinging far away from him , the beast found another target in the Imperials Wil ' m Grau and Anarine . The beast tracked them down to a tower within the city , but the Imperials were ready for it . The two men rigged the tower with explosives , and as soon as the creature entered , the supports exploded , collapsing the 200 meter tower on top of the beast . However , the power of the Sentinel was unmatched , and he pushed the pounds of rubble off of him and prepared to finish the two Imperials . However , just as the Sentinel was upon them , it sensed that the Rebels had found the city ' s main complex . Knowing that the complex was the source of its existence and understanding that it needed to protect the structure at all costs , the beast teleported away from the two men and back to the complex . The creature also reduced its size so that it would minimize collateral damage . Entering the building , the beast found Ensign Kyril Lopaki bearing down on Luke and Leia with a blaster pistol . The Ensign turned and fired on the beast , hoping that its reduced size meant that it was less powerful . However , the beast still retained its awesome power and swatted Lopaki aside , killing him . Showdown . With Lopaki dead , the beast advanced on Luke and Leia . However , the young Jedi was not going to go down without a fight , and he brought his lightsaber to bear . The power of the saber managed to damage the creature ' s hand . Unfortunately for the Jedi , the Sentinel recovered from the attack and struck out at Luke , knocking him unconscious and flinging him across the room . The creature advanced on Leia next , but before he could reach her , Anarine and Wil ' m Grau arrived to save the day , firing wildly into the room . Several of the blaster bolts hit consoles in the complex , staggering the creature . The intruders realized that the room was the creature ' s weakness , and so they began to destroy the complex . The Sentinel cried out in pain , grabbing Leia and trying to crush her within his grip . However , just at this moment , Luke revived and stabbed the Sentinel through the chest with his saber . The thrust of the laser sword disrupted the matrix that gave the creature form and created a backlash loop into the complex . The strength of the energy resulting from the creature ' s death created a massive explosion , leaving the room in flames , and the intruders thrust from the room . After several days , the group was able to dig its way out of the rubble and make its way back to a ship . The Rebels and Imperials believed the complex and the Sentinel destroyed , as the lights throughout the entire complex had turned themselves off following the incident . Personality and traits . The Sentinel was an energy creature , reptilian in appearance . It generally assumed a massive form and enjoyed toying with its enemies . During an invasion by intruders upon the city , the beast delighted in slowly tracking down its prey , and as the intruders tried to fight back , it seemed to flaunt its invincibility by taking blaster shots full on . This reaction was only seen different when the creature faced Luke Skywalker and his lightsaber , which generally hurt him . In this instance , the beast took a defensive stance , striking out wildly . The creature also generally seemed to enjoy murder and mayhem . It was known to laugh appreciatively when killing , and made its kills in a very gruesome manner , tearing the victim ' s body apart . Additionally , when the beast first searched the " Staraker " , it left a scene of destruction within the inside of the ship . This same destruction was seen when the Sentinel first attacked the archaeologists , as it ripped apart their habitat domes from the inside out , seemingly only for its own destructive needs . Abilities . The Sentinel possessed incredible powers given to it by the power of the Forever control center . It had enormous strength , and could easily rip through stormtrooper armor with its bare claws . Additionally , the beast had the power to teleport from place to place , which it demonstrated when it felt that the complex was in danger and transported itself back to its source of power . Finally , the Sentinel demonstrated the ability to change its size when it entered the complex , shrinking its size so that it would minimize damage to the delicate structure .