After the end of the InVasion angle, Chris Jericho defeated The Rock to win the World Championship (aka the WCW World Heavyweight Championship), then defeated "Stone Cold" Steve Austin directly afterwards to win the WWF Championship and unify the two titles into the WWF Undisputed Championship. To put that into perspective: Chris Jericho went from being a WCW midcarder to defeating the two biggest stars of the Attitude Era in the same night in consecutive matches to unify two of the most prestigious world titles in professional wrestling history, all in the space of three years.
2002:
The triple threat match between The Rock, Kurt Angle, and The Undertaker was a sight behold. This match was famous for all the combatants using each others' signature moves on each other. This was also the last time The Rock would win the WWE title (which was the Undisputed Championship at the time) until 10 and a half years later at the 2013 Royal Rumble.
Chris Benoit vs Eddie Guerrero in particular was one of the greatest matches for either wrestler, and included one of Eddie's Funny Moments, hitting the ref with the newly remade United States Title and then trying to frame Benoit for it by playing possum.
Also notable on the card was Vince McMahon vs. Zach Gowen. For those who do not know who Zach Gowen is, he is a one-legged wrestler. Although Gowen would go down in defeat, he would split open McMahon by dropkicking a steel chair into Vince's head and only lost because he missed a Corkscrew Moonsault.
The WrestleMania 21 rematch between Shawn Michaels and Kurt Angle proved to be another classic between the two, complete with the match ending with HBK giving Angle a Sweet Chin Music while the latter jumped from the top rope.
2011:
The event had Mark Henry and Big Show reenacting the big superplex that broke the ring way back in 2003. It ended in both of them getting knocked out and the ref calling the match a double-countout. Following that was the Last Man Standing match between John Cena and Alberto Del Rio, who proved that they didn't need the ring to have a good match.
At this PPV, five of the six Championships were on the line, and each and every one of the champions retained their titles, which is a rare sight to see.
