Invasion (also typeset as InVasion) was a professional wrestling pay-per-view (PPV) event produced by the then World Wrestling Federation (now World Wrestling Entertainment) (WWF/WWE) and presented by PlayStation. It took place on July 22, 2001 at the Gund Arena in Cleveland, Ohio. This event was initially planned to be called Fully Loaded, as it was advertised at the King of the Ring event, which immediately preceded Invasion. Invasion was the first pay-per-view to feature the ongoing Invasion storyline, which featured wrestlers from the WWF taking on a combined force of wrestlers from World Championship Wrestling (WCW) and Extreme Championship Wrestling (ECW), later known as The Alliance. The event featured WWF wrestlers facing WCW and ECW wrestlers.

The main event, dubbed the "Inaugural Brawl," was a five-on-five tag team match between Team WWF and Team WCW/ECW. The other main match was a singles match for the WWF Hardcore Championship between Rob Van Dam and Jeff Hardy. With a buyrate of 770,000, the event is the highest grossing non-WrestleMania pay-per-view in WWE history.

On March 23, the World Wrestling Federation (WWF) bought out its long-time rival, World Championship Wrestling (WCW). The last episode of WCW Monday Nitro aired on March 26, dubbed the "Night of Champions". Nitro started with WWF Owner Vince McMahon announcing a simulcast with Raw Is War later that night to address the future of WCW, during which it was revealed that Shane McMahon had bought WCW. At WrestleMania X-Seven on April 1, Shane defeated Vince in a Street Fight with some of the WCW talent in attendance, sitting in the upper level seats at the Reliant Astrodome. During May and June, WCW wrestlers interfered in matches on WWF programming. At the 2001 King of the Ring, Booker T interfered during a Triple Threat match for the WWF Championship and tossed Steve Austin through the announcers table, nearly costing him the title.

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