Panthro (ThunderCats 2011)

Panthro is a General in the kingdom of Thundera and great friends with King Claudus. In the first episode he is said, by Grune, to have been defeated in battle. Later on Grune brings out Panthro as a bargaining chip for Claudus to surrender. King Claudus ends up cutting Panthro free of his chains and then when his back is turned Panthro stabs him in the back, killing him. Shortly after, it is revealed that it was in fact Mumm-Ra disguised as Panthro.