#3 Mr. Kennedy

Mr. Kennedy was slowly and steadily establishing himself as a major heel on WWE TV, back in 2006-07. He was pushed heavily soon after and went on to compete in the Money In The Bank Ladder match at WrestleMania 23. The bout featured some of the biggest Superstars in WWE at the time, such as Randy Orton, Edge, King Booker, Finlay, CM Punk, and The Hardy Boyz. Kennedy still managed to grab the briefcase and win the match to bag an opportunity at the top title somewhere down the line. He soon lost the briefcase to Edge, who later cashed the title in on The Undertaker.
Kennedy's loss was due to the fact that he had suffered an injury in real life. Months later, Kennedy was involved in the illegitimate son storyline which was going to result in a feud between him and Triple H, culminating in a WrestleMania match. Plans were dropped for his push though, stemming from the violation of WWE's wellness policy.
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Around the same time, Kennedy had some serious backstage heat with WWE Superstar John Cena. He was utilizing his promos to get over with the crowd instead of trying to become a hated heel, and this didn't thrill Cena one bit. Jim Ross confirmed that Cena wasn't happy at how Kennedy acted.
Yeah, it did ruffle Cena’s feathers. Cena took it personally and thought, ‘OK, enough is enough.
Mr. Kennedy also had issues with Randy Orton, which were instrumental in his WWE release in 2009.