#3 The Undertaker

Every Superstar that The Fiend has beaten so far has been smaller than him. There has been nobody who can match up physically to him. So far, everybody on this list is bigger than Bray Wyatt. That pattern continues here, with The Undertaker.He hasn't wrestled since that extremely fun tag team match alongside Roman Reigns at Extreme Rules, so expect the Deadman to rise sooner rather than later. 'Taker is the perfect supernatural counterpart for The Fiend. The ultimate hero who could vanquish the evil monster.
The two shared the ring multiple times, as Undertaker dominated Wyatt and his family throughout 2015. Defeats at the hands of The Undertaker at WrestleMania and Survivor Series left the Eater of Worlds struggling to gain momentum.
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Now that he has buckets of it, maybe it is time to collect that debt from the Deadman. This would be the perfect program for The Undertaker to retire from if it were to ever happen.
A match between The Fiend and The Undertaker would not be technically great, but as a spectacle, nothing would come close. The aesthetic of it makes it worth a try at the very least. Maybe, we get a little passing of the torch at WrestleMania?