2. Kane
Undertaker's half-brother, the big red monster Kane has faced the Undertaker at WrestleMania, however, the final showdown should contest one of the best matches ever, the Undertaker facing Kane. Obviously, the brothers of destruction have a lot of history together. Sources have said that the only reason that the character of Glen Jacobs debuted, was because of the Undertaker. They were the two most iconic characters in the WWE, and there's no doubt in my mind that if there was no Undertaker, there would have been no Kane, and vice-verse. Imagine: it's the Undertaker's final match. What would be a better way to end his career rather than facing Kane? Both these superstars are excellent performers and are amazing on the microphone. Kane and the Undertaker would easily have a five star bout and it would be a fitting end to the Phenom's career. The WWE can make this happen, and they certainly should, cause a Kane/Undertaker feud, one last time, is money.