Appo, whose clone trooper designation was CC-1119, was a clone trooper officer who served as a Clone Sergeant and later as a Clone Commander in the 501st Legion during the Clone Wars. 

The 501st Legion, also known as Vader’s Fist, was an elite unit of clone troopers in the Grand Army of the Republic during the Clone Wars. They were known for their blue markings and their close association with Jedi General Anakin Skywalker and Commander Ahsoka Tano. The 501st played a significant role in many battles and were instrumental in the execution of Order 66, turning on the Jedi. They later became a prominent stormtrooper unit in the Imperial era.