The 2004 Royal Rumble was the 17th annual Royal Rumble 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 January 25, 2004, at the Wachovia Center in Philadelphia, Pennsylvania. As has been customary since 1993, the Royal Rumble match winner received a world championship match at that year's WrestleMania, in this instance, WrestleMania XX. Beginning with this Royal Rumble, the winner could choose which championship to challenge for at WrestleMania, either Raw's World Heavyweight Championship or SmackDown!'s WWE Championship.

Six professional wrestling matches were featured on the event's supercard, a scheduling of more than one main event. The main event was the 2004 Royal Rumble match, which featured wrestlers from both brands. SmackDown!'s Chris Benoit, the first entrant, won the match by last eliminating Big Show, also from SmackDown!. This win resulted in Benoit breaking the longevity record last held by Bob Backlund, staying in the match for over one hour, but was then broken by Rey Mysterio in 2006. Benoit also became the second wrestler to win the match as the first entrant, after Shawn Michaels. The primary match on the Raw brand was a Last Man Standing match between Triple H and Shawn Michaels for the World Heavyweight Championship, which ended in a draw. The predominant match on the SmackDown! brand was Brock Lesnar versus Hardcore Holly for the WWE Championship, which Lesnar won to retain the championship. The featured match on the undercard was a tables match for the World Tag Team Championship between Evolution (Ric Flair and Batista) and Dudley Boyz (Bubba Ray Dudley and D-Von Dudley), which Evolution won to retain the titles.