WrestleMania 31 was the 31st annual WrestleMania professional wrestling pay-per-view (PPV) and livestreaming event produced by WWE. It took place on March 29, 2015, at Levi's Stadium in the San Francisco Bay Area town of Santa Clara, California. Nine matches were contested at the event, including two matches on the Kickoff pre-show.

In the main event, Seth Rollins cashed in his Money in the Bank contract as the scheduled match between defending champion Brock Lesnar and Roman Reigns was in progress, and won the resulting impromptu triple threat match to capture the WWE World Heavyweight Championship. In other prominent matches, The Undertaker (in his first on-screen appearance since the previous year's event) defeated Bray Wyatt and John Cena defeated Rusev to win the WWE United States Championship. The event was also notable for Sting's debut match in WWE, as well as his only WrestleMania match, in which he was defeated by Triple H.

Despite criticism for its build-up and retrospective criticism for the booking decisions, the event received highly positive reviews from fans and critics alike; some critics called it one of the greatest WrestleManias of all time. Praise was focused on the quality of a vast majority of the matches, the ending of the main event, and lack of matches considered to be "filler", while the women's tag team match was subject to this very criticism. Retrospective criticism has been focused on Triple H's win over Sting, which was viewed as an unnecessary ode to WWE winning the Monday Night Wars. WWE reported that the show was the highest grossing WWE event ever, drawing a revenue of $12.6 million. The company also claimed an attendance figure of 76,976. This was also the first WrestleMania to incorporate WWE's current logo that was originally used for the WWE Network.