Giant Gonzales - As a little kid, I was thinking to myself "OMG, look at the size of that guy! How is Undertaker going to beat him?!!"
Diesel - This is when The Streak became a big deal as Nash was a former WWF Champion.
Sid - Definitely a threat as he had beaten Shawn Michaels and Bret Hart back to back.
Kane - Was undefeated heading into Boston and the poetic notion if anybody could beat Undertaker at WM, it would be his brother.
Helmsley - I knew Undertaker was winning, but HHH defeating Stone Cold the month prior definitely gave him some credibility. The final encounter in Miami though was the best example of "All Or Nothing" storytelling as Undertaker was the underdog heading into the match.
The Big Show & A-Train - The match turning into a handicapped one raised the stakes and was nail biting to watch.
Orton - If anybody should've ended the Streak, it was this man.
Batista - The last true challenge to the Streak IMO as nobody had been able to defeat Dave for the title. This is my favorite Undertaker WM match with Edge being a close second.
Michaels - The greatest battle though as The Dead Man had never defeated HBK before plus it was fantastic that The Undertaker was having his mind toyed with by his opponent for a change.