WrestleMania 21 (marketed as WrestleMania Goes Hollywood) was the 21st annual WrestleMania professional wrestling pay-per-view (PPV) event produced by World Wrestling Entertainment (WWE). It was held for wrestlers from the promotion's Raw and SmackDown! brand divisions. The event took place on April 3, 2005, at Staples Center in Los Angeles, California.

The main event of the show, which was the main match from the Raw brand, saw Batista challenge Triple H for the World Heavyweight Championship, which Batista won by pinfall after executing a Batista Bomb. The main match on the SmackDown! brand, which was the event's penultimate match, saw John "Bradshaw" Layfield (JBL) defend the WWE Championship against John Cena, which Cena won by pinfall after performing an FU marking Cena's first world title reign of his world record sixteen.

The undercard featured the first-ever Money in the Bank ladder match, as well as two inter-promotional matches with Randy Orton vs. The Undertaker and Kurt Angle vs. Shawn Michaels. The event also featured the return of Stone Cold Steve Austin who then started his part-time appearances with WWE and also the final WrestleMania event that Eddie Guerrero competed in, going against his tag team partner Rey Mysterio. Guerrero succumbed to heart failure in November that same year.

WrestleMania 21 was the first WrestleMania held at Staples Center, but the fifth to take place in the Los Angeles metropolitan area (after 2, VII, XII, and 2000). Tickets sold out in less than one minute for the event, making it the fastest ticket sell-out in the company's history as well as the fastest ticket sell-out at Staples Center. The event drew a Staples Center record attendance of 20,193 people from 37 countries and 50 states and grossed more than $7.1 million in ticket sales, making it the highest grossing WWE event ever at Staples Center. In addition to those in attendance, the event was seen by millions of fans in more than 190 countries.