Who vowed to break The Undertaker's WrestleMania streak for the first time? 

On February 28, 2005, Superstar Billy Graham made an appearance on RAW and advised Randy Orton "to step up and go where no wrestler has gone before." After Superstar Billy Graham left the scene, Randy Orton dropped a Smackdown Magazine which featured The Undertaker on cover.

He then cut the first promo for a potential feud with The Undertaker for WrestleMania. After Superstar Billy Graham wished him luck and left by stating, "That was actually exactly what I was thinking."

The SmackDown copy had The Undertaker featured on the cover page with the caption, "The legacy on the line." The cover page also stated, "The Undertaker takes his 12-0 record to WrestleMania 21."

During Randy Orton's infamous Legend Killer gimmick, Orton eyed every major superstar of the era. The legends, as the WWE had so famously tagged the older wrestlers, were victims for a young eccentric and ready to take anything Randy Orton.

When I heard the word "Victim" in the last episode of Smackdown Live from Randy Orton, I was somehow convinced that this was Randy Orton, The Legend Killer. Even though he hasn't made it official, or WWE hasn't used the word yet, Randy Orton used to choose his victims and then destroy them.

That time, it was The Phenom. The entire March, Randy Orton acknowledged inside the ring that he would break The Undertaker's WrestleMania streak. The Legend Killer vs Legend match between The Undertaker and Randy Orton created great amount of noise in the WWE Universe.

This was The Undertaker's 13th WrestleMania match, but it was actually Randy Orton in his Legend Killer gimmick who finally addressed to the world that he will go where no wrestler had gone before and break The Undertaker 12-0 streak back then.

It would have been really nice if Randy Orton ended up being the wrestler who ended The Undertaker's streak as he was the one who actually acknowledged it in the first place.

At WrestleMania 21, the much hyped match was a losing effort for Randy Orton, but the match is still the closest you will get to beating The Undertaker, with a chokeslam converted into an RKO. Randy Orton mimicking The Undertaker's trademark sign trying to follow it up with a tombstone to The Undertaker ended in failure.

The match had the hype, the fans cheering at the top of their voice and everything one would have needed from The Undertaker performing at WrestleMania. Ever since then, it hasn't been anything about the belts, but more importantly about The Streak.