2. Muhammad Ali
In my opinion, he was the first Special Guest Referee of any importance. Officiating the very first WrestleMania main event of Hulk Hogan/Mr. T vs. Roddy Piper/Paul Orndorff, a worldwide hero in the form of the best boxer ever born would be a humungous asset in cementing WrestleMania as the company's best event. Even more notable is the ending of the match, where Ali knocked out Piper by punching him straight in the mush, creating one of the most famous photos in WWE's history. The prospect of seeing Ali strut his stuff around the ring while refereeing would be really fun, and can just imagine him taking all the attention away from the action in the ring. Technically a terrible ref then, but you know...