#2 Shawn Michaels - Prevented Vader from winning the WWE Championship at SummerSlam 1996

Shawn Michaels was the face of WWE in 1996. At WrestleMania 12, he defeated arch-rival Bret Hart to capture the WWE Championship for the first time. His first reign as WWE Champion would go on for over half a year, facing some top names as his challengers.
One of the biggest challenges (literally) that Shawn Michaels faced in that reign was Vader. The wrestling legend was supposed to be booked to win the WWE Championship from the smaller HBK, but backstage politics prevented it.
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When Shawn Michaels was WWE Champion in 1996, it was perhaps the peak of his ego. Before changing his life in the late 1990s and early 2000s, Shawn Michaels wasn't considered to be a very nice person as per multiple accounts.
Jim Cornette had a less-than-flattering account of Shawn Michaels and his refusal to lose to the late great Vader. While not directly implying it, Cornette accused the WWE legend of "refusing to do jobs" for other superstars.
In an interview, Vader admitted that he was promised a WWE title win.
"You know what, the title was promised to me two times. I was supposed to be a two-time heavyweight champion. If I did the job for Shawn at SummerSlam, and then something would happen and I'd get it then give it to somebody else, take it back and then give it back to Shawn in San Antonio. Instead, somehow that got changed around," said Vader.
With that said, Vader doesn't seem to be as bitter about it. In an interview with Hannibal TV, he seemed to be more accepting of what happened. While admitting that WWE could have done a better job rather than having him lose to Shawn Michaels so much, he went on to praise The Heartbreak Kid as an all-time great - saying "Shawn, in his prime, I don’t know if there is another better worker.”
Sycho Sid got his spot instead. At Madison Square Garden, he captured the WWE title from Shawn Michaels before losing it in the latter's hometown of San Antonio two months later in the 1997 Royal Rumble.
Soon after that, Shawn Michaels "lost his smile" and vacated the WWE Championship.