#3 Batista

This wasn't necessarily set in stone but pitched various times in the past few years. Batista has mentioned in various interviews that he is all in for a WWE return and has even spoken to Vince McMahon about the same, only to get a "meh, we'll think about it" in return.
However, McMahon was interested in getting the Animal back as a special guest referee for the Triple H vs Roman Reigns WrestleMania 32 match. Batista turned it down and was clearly not over his failed return from a few years prior to that.
The less we talk about Batista's last run with the company the better. Despite leaving a bitter taste in his mouth, the 6-Time WWE Champion wants to put the past behind him and return for one last match against the man that played a significant role in making him a top star, Triple H himself.
The Animal revealed on Talk is Jericho that he misses the world of pro wrestling -- the live events, traveling, the fans and the adrenaline rush that comes along. He condemned the bs that goes on backstage and just put out one condition on his full-time comeback -- another feud with The Game.
Being on the wrong side of the 40s, time is running out both for the WWE and one of the more successful Hollywood imports produced by the company.