10. The UndertakerI'll start with a fairly easy to predict one. The Undertaker has spent a bizarrely large amount of time on WWE TV in 2015, and a lot of it felt like it was part of a nostalgia tour before his impending retirement. He made his debut in 1990 and is by far the longest active member of the roster. His career is without parallel, and saying he has nothing left to prove is like saying that the sun tends to be a little warm. He also happens to be 50 years old, and every passing year seems to invoke some sort of discussion on his physical state. Sure, he does things in his sixth decade that I can't do now, but the sun is setting on the career of the Deadman and rightly so. WrestleMania XXXII is taking place in his home state of Texas and WWE are looking to break all sorts of attendance records at the show. The show will serve as Taker's last ride, as surely a showdown with John Cena or Sting is on the cards. He will then walk slowly into the sun, leaving behind an untouchable career.