#1 Brock Lesnar
He may have only just lost the Universal title, but it seems Brock Lesnar's days with WWE may be numbered. The only man to hold the title twice, the company see Brock as a huge draw, and rightly so. During his first 500+ day reign as champion, Lesnar’s appearances were both must-see and can’t miss.
His second reign was similarly impressive, though rumors of conflicts backstage have plagued the Beast and advocate Paul Heyman for a while now. No longer the Universal Champion, Lesnar reportedly left WrestleMania 35 early after his opening match against Seth Rollins, a not-so on the nose metaphor for the Beast's possible plans.
With a match against Daniel Cormier still rumored, it seems Brock has been bitten by the UFC bug, and expect him to return to the octagon in 2019.