#1 Triple H
The third superstar to have defeated both Brock Lesnar and The Undertaker is the COO of WWE, Hall of Famer, the King of Kings, Triple H.
Triple H has faced the Undertaker thrice at WrestleMania but has never been able to defeat the Dead Man. But last year at the Super ShowDown PPV in Australia, Triple H pinned The Undertaker in their No Disqualification match, with some help from two of his best friends, Shawn Michaels, and the Sledgehammer.
He then also went on to defeat The Brothers of Destruction alongside Shawn Michaels as D-Generation X in his comeback match at the Crown Jewel PPV in Saudi Arabia.
As for Brock Lesnar, the Cerebral Assassin faced the Beast at WrestleMania 29 in a No Holds Barred match with Triple H's career on the line. In what was a grueling match, Triple H managed to pin the Beast after delivering a Pedigree to him on the steel steps.
Which current WWE Superstar do you think can join this list in the near future? Do let me know in the comments section.