#2. Floyd Mayweather - Had a match in WWE against The Big Show
Floyd Mayweather wasn't a popular boxer, nor was he popular in WWE when he appeared. At No Way Out 2008, Floyd Mayweather saved Rey Mysterio from Big Show, with WWE presenting the boxing legend as a babyface.
It wasn't met with a great reception from fans, as Floyd Mayweather's personality outside the ring wasn't popular. Big Show's nose was broken by Mayweather in that attack and the wrestling legend challenged him to a match at WrestleMania 24.
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In a No DQ bout, Floyd Mayweather defeated Big Show. He would appear on RAW over 16 months later in 2009, assisting MVP and Mark Henry to defeat Jeri-Show.
#1. Mike Tyson - One of the most important sports star appearances?
Mike Tyson's appearance and WWE run for WrestleMania 14 couldn't have been more perfectly timed - at least from one point of view. Mike Tyson was coming off his highly controversial DQ loss to Evander Holyfield, where he infamously bit his ear.
Even then, Mike Tyson was arguably the biggest sports star in the world and WWE capitalized on it by having him sign on for a run leading up to WrestleMania 14. At the time, Tyson was aligned with DX, led by Shawn Michaels.
Shawn Michaels was to defend the WWE Championship against 'Stone Cold' Steve Austin in the main event of WrestleMania 14. While Mike Tyson was originally the scheduled special guest referee, he was turned into a ring enforcer for the main event.
It was an incredible storyline that was meant to coronate 'Stone Cold' Steve Austin as the face of WWE. Tyson and Austin even got involved in an altercation. However, at WrestleMania 14, Tyson was the one who counted the pinfall as Austin won his first World Championship.
After the match concluded, a furious Shawn Michaels was knocked out by the heavyweight legend. He also famously knocked out Chris Jericho on RAW years later.