#3 His longevity
The Undertaker made his WWE debut on camera at Survivor Series way back in 1990, where he eliminated two future WWE Hall of Famers, Koko B. Ware and Dusty Rhodes.
He wrestled his apparently final match at Wrestlemania 33 in 2017. That's a 27-year career that has been filled with nothing but awesome success. It has always seemed like every time he was done, he came back for one more match.
How does anyone ever replicate that? Especially considering the magnitude of his matches and how good they were on a consistent basis. The answer? No one replicates that.