WWE Greatest Royal Rumble was a professional wrestling pay-per-view (PPV) and livestreaming event produced by the American company WWE. It was held for wrestlers from the promotion's Raw, SmackDown, and 205 Live brand divisions. The event took place on April 27, 2018, at the King Abdullah Sports City's King Abdullah International Stadium in Jeddah, Saudi Arabia. It was the first in a series of WWE events held in Saudi Arabia in support of Saudi Vision 2030, the country's social and economic reform program. At the event, all men's main roster championships at the time were defended, in addition to a 50-man Royal Rumble match, titled the Greatest Royal Rumble match.

The card comprised 10 matches. In the main event, Raw's Braun Strowman won the Greatest Royal Rumble match to win the WWE Greatest Royal Rumble Trophy and Championship. In the penultimate match, Brock Lesnar retained Raw's Universal Championship against Roman Reigns in a steel cage match. In other prominent matches, SmackDown's WWE Championship match between defending champion AJ Styles and Shinsuke Nakamura resulted in a double countout, The Undertaker defeated Rusev in a casket match, and in the opening bout, John Cena defeated Triple H. The Greatest Royal Rumble match was notable for being Chris Jericho's final match in WWE; Jericho had been employed off-and-on with the company since 1999. After making a few appearances in New Japan Pro-Wrestling, Jericho became one of the first wrestlers to sign with All Elite Wrestling in 2019. The match was also the last match in The Great Khali's and Mark Henry's wrestling career and the last match where Hornswoggle wrestled for WWE. The match was also Hiroki Sumi's only match in WWE.