The 2001 No Mercy was the fourth No Mercy professional wrestling pay-per-view (PPV) event produced by the World Wrestling Federation. The event took place on October 21, 2001, at the Savvis Center in St. Louis, Missouri. It was the final No Mercy event held under the WWF name as the promotion was renamed to World Wrestling Entertainment (WWE) in May 2002. It was also the final No Mercy held before the introduction of the brand extension in March 2002.

The Enterprise Center is an 18,096-seat arena located in downtown St. Louis, Missouri, United States. Its primary tenant is the St. Louis Blues of the National Hockey League, but it is also used for other functions, such as NCAA basketball, NCAA hockey, concerts, professional wrestling and more. In a typical year, the facility hosts about 175 events. Industry trade publication Pollstar has previously ranked Enterprise Center among the top ten arenas worldwide in tickets sold to non-team events, but the facility has since fallen into the upper sixties, as of 2017.