Sheng Long

Originally a prank based on a mistranslation, Shang Long was suppossedly a character who could be unlocked in Street Fighter.

Origin
Sheng Long was originally meant to mean "Rising Dragon punch" and the player was told "If you can't overcome my Rising Dragon Punch, you can not win." But Sheng Long wasn't translated into English, so the player was told that they had to beat Sheng Long, gamers misunderstood the statement, believing there was an actual character they had to beat.