WrestleMania XX was a 2004 professional wrestling pay-per-view (PPV) event produced by World Wrestling Entertainment (WWE). It was the 20th annual WrestleMania and took place on March 14, 2004, at Madison Square Garden (MSG) in New York City, New York, held for wrestlers from the promotion's Raw and SmackDown! brand divisions.

This was the third WrestleMania at MSG, after WrestleMania I in 1985 and WrestleMania X in 1994, and the fourth of six WrestleManias in the New York metropolitan area, including WrestleMania 2 in 1986, WrestleMania 29 in 2013, and WrestleMania 35 in 2019. It was also the last WrestleMania at MSG as WWE began to run only stadiums for the annual event beginning with WrestleMania 23 in 2007, excluding WrestleMania 36 in 2020, which was held at the WWE Performance Center behind closed doors due to the COVID-19 pandemic. WrestleMania XX's calendar date of March 14 was the earliest date for a WrestleMania.

The match card featured two billed main events. The card's final match, which was the main event for the Raw brand, was a triple threat match for the World Heavyweight Championship, which saw champion Triple H defending the title against Shawn Michaels and that year's Royal Rumble match winner, Chris Benoit, who won the match, making Triple H submit via the Crippler Crossface, resulting in his first and only world championship in WWE. The main event for the SmackDown! brand featured Eddie Guerrero versus Kurt Angle for the WWE Championship, which Guerrero won by a Small Package pin. The event also featured the return of The Undertaker in his Deadman persona, who defeated Kane after a Tombstone Piledriver. John Cena made his in-ring WrestleMania debut at the event, defeating Big Show to win his first title in WWE, the WWE United States Championship.

Also on the card was a match between Goldberg and Brock Lesnar with "Stone Cold" Steve Austin as the special guest referee. This was both Lesnar's and Goldberg's final match in WWE until Extreme Rules 2012 and Survivor Series 2016, respectively. After Goldberg won the match following a Jackhammer, both men were given a Stone Cold Stunner by Austin on their way out. The event also featured the in-ring return of The Rock, teaming up with Mick Foley and reuniting the Rock 'n' Sock Connection to take on Evolution (Randy Orton, Batista, and Ric Flair) in a 3-on-2 Handicap match, in which Evolution were victorious. This would be The Rock's final match in WWE until Survivor Series 2011.

The event grossed US$2.4 million in ticket sales, making the pay-per-view the highest grossing event ever for WWE at MSG.[3] More than 20,000 people from 16 countries and 48 U.S. states attended the event, which was also televised in more than 90 countries.[4] The event generated an estimated $13.5 million of economic activity for New York City and created an equivalent of 96 full-year jobs.[5]