In August 2002, Rey Mysterio entered WWE. His first major feud was with Kurt Angle, and the two had a phenomenal match at SummerSlam. Shortly thereafter, Rey Mysterio set his sights on the WWE Cruiserweight champion Matt Hardy, although he failed in his first title shot at WrestleMania XIX. Rey Mysterio won the championship a few times, as well as the WWE Tag Team Championship with Edge, Rob Van Dam, and Eddie Guerrero, but it wasn't until he won the Royal Rumble in January 2006 to garner a title shot at WrestleMania 22 that he was thought of as a headliner. Rey Mysterio upset Kurt Angle and Randy Orton to win the World championship. He successfully defended the championship at WWE Judgment Day against JBL before dropping the title to King Booker at Great American Bash.
Rey Mysterio remained the most popular Mexican-American performer in WWE for several years, and he had a lengthy reign as Intercontinental Championship from April 2009 until September (that reign actually had a 3-week hiccup by Chris Jericho). In June 2010, he regained the World Heavyweight championship in a Fatal Four-way at the expense of Jack Swagger; unfortunately, Kane crushed him for the championship the next month at Money in the Bank.