The 2005 SummerSlam was the 18th annual SummerSlam 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 August 21, 2005, at the MCI Center in Washington, D.C. Nine matches were contested at the event, including one on the Sunday Night Heat pre-show.

The main match on the Raw brand was Hulk Hogan versus Shawn Michaels, which Hogan won by pinfall after executing a leg drop. The predominant match on the SmackDown brand was a No Holds Barred match for the World Heavyweight Championship between Batista and John "Bradshaw" Layfield (JBL), which Batista won by pinfall after executing two Batista Bombs, with the second on the steel ring steps. Another primary match on the Raw brand was for the WWE Championship between John Cena and Chris Jericho, which Cena won by pinfall after performing an FU. The main match on the undercard featured a ladder match for the custody of Rey Mysterio's son Dominik between Mysterio and Eddie Guerrero, which Mysterio won by retrieving the briefcase suspended above the ring.