#1 Bray Wyatt

The Undertaker has faced and defeated some of the greatest Superstars in WWE history during his long run in the company, but never has he come across a character as twisted and sinister as The Fiend.
The Undertaker feuded with Bray Wyatt back in 2015, a year after Brock Lesnar brought an end to The Streak. Despite Wyatt's claims and cryptic promos, The Deadman stood tall at the end of the whole ordeal.
However, things have changed now. While the comparisons between Wyatt and The Undertaker made sense even back then due to the dark characters that both the men played, the similarities are more resounding now.
Just like The Undertaker, The Fiend is able to instill fear in the hearts of his opponents merely with his presence. Him appearing out of nowhere to make a vicious attack on unsuspecting victims is very reminiscent of The Undertaker making his presence felt inside the ring following the toll of the bell and chokeslamming a numb opponent.
The Fiend has been going after everyone that wronged him during his previous gimmicks and perhaps The Undertaker could be on his list. For The Deadman, this would be an opportunity to prove to the world yet again that nobody can recreate the enigma of the one and only Undertaker.