2: Sting
For years, the Icon Sting was considered arguably the greatest ever star to never step foot in a WWE ring.
That all changed in November 2014, when Sting appeared at the company's Survivor Series event, drawing the ire of Triple H.
Coming up short against the Game at WrestleMania 31, Sting would set his sights on the WWE World Championship later in the year, meeting against Seth Rollins.
During the match, the Architect hit the Stinger with a buckle bomb, which severely damaged the legendary star's neck.
After being diagnosed with cervical spinal stenosis, Sting was forced to walk away from the ring and announced his retirement at his WWE Hall of Fame induction in 2016.
Now retired, it seems that fans will never get to see the dream match of the Icon Vs. The Undertaker.