What Could Have Been: Both good and bad. Originally, Vader was supposed to go over Shawn Michaels for the WWE Championship at SummerSlam 1996, but Shawn vetoed that, as he was in ego mode at the time. And according to Jim Cornette, upon signing with WWE, Vince McMahon wanted Vader to change his name to The Mastodon, as that way they could trademark the name as they couldn't trademark Vader.note Due to George Lucas owning the name "Darth Vader." Cornette luckily talked Vince out of this move.
Knowing his experience and popularity in shoot-style, Mixed Martial Arts company PRIDE Fighting Championships once wanted to bring Vader as a fighter, and he actually started to train in the Team Hammer House. At the end, however, the DSE management opted not to book him in MMA bouts after seeing his poor physical condition in his only match in HUSTLE.
WrestleCrap: The Baywatch episode "Bash at the Beach." Go here for an explanation. It's too stupid to type up again.