Gregor, formerly designated CC-5576-39 [shortened to CC-5576], served as a Clone Captain in the Grand Army of the Republic's Special Operations Brigade. He was assigned to the 212th Attack Battalion of the 7th Sky Corps under Jedi General Obi-Wan Kenobi and Clone Marshal Commander CC-2224 'Cody'.
For the Battle of Sarrish, Gregor and his men were assigned to Foxtrot Group, an elite Clone Commando squad. The battle proved to be a great defeat for the Republic, and Gregor was forced to retreat into space, later declaired as 'Missing in Action' by official records.
His transport ended up crash landing on Abafar. The crash caused him to suffer from amnesia, and he was rescued by a Sullustan named Borkus who took advantage of his condition to put him to work as a dishwasher in his business.
Gregor regained his memories after Colonel Meebur Gascon and his all-droid unit 'D-Squad' identified him after their chance arrival in Pons Ora. He assisted his fellow soldiers in escaping by re-possessing a Separatist-stolen shuttle in the Ridonium Mines. Unfortunately, they were confronted during their efforts and Gregor took action. He was thought to have been killed in an explosion trying to protect the Colonel and his companions in a firefight against Separatist Droids after decaring a promise that he would find his way home.
Miraculously, he survived the explosion, although he sustained a traumatic brain injury. Despite that he was returned to duty after being rescued and recovering from the physical wounds.
After the Clone Wars ended, Gregor was sent by the new Galactic Empire to a secret facility on the planet Daro, where he and other Clone Commandos were tasked with training the 'TK Troopers' which were to replace the Clones via Imperial Project War-Mantle.
Gregor quickly realized he wanted out and sent a distress signal to the Clone deserter Captain CT-7567 'Rex', who was unable to come himself but sent to the rogue Clone Commando Sqaud, Clone Force 99 or 'The Bad Batch', to rescue him.
Fifteen years after the end of the Clone Wars, Gregor was still alive and was living in a modified AT-TE on Seelos with Captain Rex and Clone Commander CC-3636 'Wolffe'. All three having retired and spending their days hunting the mighty sand worms called 'juupa'.
One year before the Battle of Yavin, Gregor participated in the Liberation of Lothal, where the Lothal Resistance Group and the Rebel 'Spectres' cell drove the Galactic Empire off-world once and for all. During the conflict, however, Gregor was mortally wounded and passed away in Rex's arms, telling him that it was an honor to serve with him and to fight for a cause the Clones actually chose to believe in.
