Both the Iconic professional wrestler of their worlds. Both finish with pile drivers. Huge, powerful men. I say that Zangief can not deal enough punishment to The Undertaker to put him away. Kinda goofy, but wanted some thoughts.
I am going for the character not the normal human man behind the hat. The undertaker has survived the grave. Defeated every superstar wrestler for the past 2 decades. Has never been defeated at Wrestlmania; and he has every freak of a gigantic human put in his path only to knock everyone of them down.(I.E. Diesel, The Big Show, Psycho Sid, Kane, The giant Gonzalez, Yokozuna, The great Kali.) All Bears of men with huge legends. He has survived the stone cold stunner, the tombstone piledriver, the pedigree, the rock bottom, the super kick, choke slam, AA, GTS, and the Hulk Hogan leg drop. He does not wrestle bears but he walks on a different plane of existence. Again I am going for his legend not he man. what do ya think?
Hm, not a real follower of wrestling but I suppose of he is a mythical revenant-type character this may be closer. Zangief is still powerful though, the fact that he can survive Blanka's electricity attack alone gives him incredible durability, and the physics behind an across-the-screen Spinning Piledriver makes him an outrageous physical specimen.
Undertaker as a character stomps! Undertaker as a normal person in his prime, still an amazing athlete. He jumped from the mat, over the top rope, over a casket that was outside the curtain, and into 3 people at one of the Wrestlemanias (can't remember which one), oh ya, and he was in his 40's when he did that.