The 2003 SummerSlam was the 16th 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 August 24, 2003, at the America West Arena in Phoenix, Arizona.

SummerSlam is a professional wrestling event, produced annually since 1988 by the world's largest professional wrestling promotion, WWE. Dubbed "The Biggest Party of the Summer", it is considered WWE's second biggest event of the year behind their flagship event, WrestleMania. It is also considered one of the company's five biggest events of the year, along with WrestleMania, Royal Rumble, Survivor Series, and Money in the Bank, referred to as the "Big Five". The event has been broadcast on pay-per-view (PPV) since the inaugural 1988 event and via livestreaming since the 2014 event.