TK-138, otherwise known as Roy, was a Stormtrooper assigned to Base 327 in 2 BBY. Because of his unwillingness to serve at this base, the Imperial officer on Coruscant giving assignments conceded and let him only have to serve for a week unless he changed his mind. After his week was over, as he was about to leave, his TIE Fighter literally fell apart and caught fire. This was later revealed to have been done by Bomby and Bomber (supposedly as their last prank).
Roy's number could be a reference to THX-1138, George Lucas' first movie before Star Wars.Roy is one of the smarter clones at base 327