CC-1119 was a clone trooper commander who served in the Grand Army of the Republic as the commander of the elite 501st Legion. During the Clone Wars, CC-1119 received training from the ARC trooper Alpha-17, where he was given the name "Appo." Around 21 BBY, Appo, who was a clone sergeant at the time, was part of a Republic battle group that was sent to the Confederate planet Umbara. In the war's final year, Commander Appo led the 501st Legion in a Republic attack on the Jedi Temple. He served under Darth Vader during the Temple attack and later, when the Republic transformed into the Galactic Empire. Appo and his soldiers became some of the first Imperial stormtroopers, and alongside Vader he worked to suppress threats against the Empire.
A month after its creation, he and his men saved Vader's life in a Jedi ambush on Kessel. In the following weeks, Appo was stationed aboard Vader's Imperator-class Star Destroyer Exactor. He helped Vader to hunt down a group of clone traitors who had aided the escape of Jedi on Murkhana, then continued to aid Vader in the search for those Jedi. The chase took him from Murkhana to the Jedi Temple to Alderaan, where the path of the fugitive Jedi intersected that of Senator Fang Zar—a wanted man by the Empire—and at last to Kashyyyk. As the Empire invaded that world later in the year, Appo accompanied Vader to the planet's surface in pursuit of the Jedi, only to be decapitated by Jedi Master Roan Shryne.