Undertaker (Retro) is the champion of WWE 2K14. An 8 man King of the Ring tournament is started, with the winner having the chance to fight Undertaker (Retro) for the title and take his belt. Undertaker (Retro) is never referred to simply as Undertaker, as the game forced SuperGreatFriend to call him by this name. The modern Undertaker does not get a tag attached to his name. This has provided much hilarity for the stream as they talk about how "retro" he is, to the point characters within the universe began to refer to him by his full name or even just "Retro".
Undertaker (Retro) is the WWE's version of the grim reaper, and has some supernatural powers over the dead, first warning Bully Demise that Killerman has a controller. His belt holds unimaginable power, and he does his best to keep it out of evil hands. The power of this belt appears to be why he bothers with something as trivial as the WWE. It is the goal of The Mystic to have Killerman win the King of the Ring tournament and defeat Retro to claim this power for himself.