#3 Mordecai
Poor Kevin Thorne. The weight of expectations of becoming the next Undertaker gave us one of the biggest failures of the Ruthless Aggression Era. In WWE's defense, he wasn't the quickest of learners either.
WWE was quite serious on Undertaker putting over a rising developmental talent Kevin Thorne back in 2002 and eventually called up him under the name Mordecai to SmackDown as a religious fanatic hell-bent on eliminating sin from the world.
He wrestled three matches in total, forced the fans to prayer and was unceremoniously sent back to developmental after being on the main roster for just a month. Initially primed to be the Undertaker's opponent, WWE had to drop the plans and decided Throne needed more training.
Putting a mask on him proved to be the final nail in the coffin for Thorne as he was released from his contact in 2005. He returned for another tormenting run in WWE's reboot of ECW as a Vampire along with his valet named Airel. Amusingly enough, he was yet again sent to WWE's developmental system Ohio Valley Wrestling, before being kicked out for good in 2009.