Fordo

“Clankers forces inbound sir, approaching from all sides!” -Fordo to Yoda at the battle of Coruscant
Fordo, also known by the designations Alpha-77 and ARC-77, was an Alpha-class Advanced Recon Commando captain in the Grand Army of the Republic born on Kamino. He went through Alpha’s 17 ARC training program alongside many other clone brothers. He formed a close friendship with CT-7567, or Rex. The two would paint matching Jaig eyes on their armor, a Mandalorian symbol which symbolized a marking of great feats of honor or courage. Fordo would part ways with Rex in the beginning of the war, with his friend being assigned to the 501st Legion, and Fordo being assigned to advanced special missions with a small squad. 
In 22 BBY, he was assigned to a task force led by the Jedi Knight General Obi-Wan Kenobi, to take the Confederate-held world of Muunilinst. Together with a group of clone troopers that would later come to be known as The Muunilinst 10, Fordo proved instrumental in the Battle of Muunilinst, leading his troops to destroy an enemy artillery emplacement, and then helping Kenobi capture the enemy leader, San Hill.
Immediately after the battle was over, Fordo was dispatched to the planet Hypori, where a group of Jedi Knights had been trapped by the Confederate General Grievous. Making their way to the Jedi's location, Fordo and his men battled Grievous, but were unable to kill him. They were, however, able to recover three survivors: Ki-Adi-Mundi, Aayla Secura, and Shaak Ti. Fordo would come across Rex’s path again during the Battle of Agamar, his squad working in tandem with the 501st to overcome the Separatist armies, with Fordo conversing with Rex and his commanders, Jedi General Anakin Skywalker and Jedi Padawan Ahsoka Tano. The group eventually won the battle, and Rex and Fordo parted once more. 
In 19 BBY, Fordo was on Coruscant when the planet was attacked by the Confederacy. Despite facing overwhelming numbers, Fordo and his men were able to beat back a portion of the attacking force in Sector Four with the help of Jedi Masters Mace Windu and Yoda. After the Battle of Coruscant and Order 66, Fordo and his squad were brought into the Galactic Empire and Imperial Military.