The 2001 Vengeance was the inaugural Vengeance professional wrestling pay-per-view (PPV) event produced by the World Wrestling Federation. It took place on December 9, 2001, at the San Diego Sports Arena in San Diego, California. The event replaced the promotion's usual December PPV, Armageddon, for the year 2001; Armageddon was reinstated in 2002 with Vengeance moved up to July. The theme music for the event was performed by Drowning Pool and was called “Sinner”. It was also the only Vengeance event promoted under the WWF name as the promotion was renamed to World Wrestling Entertainment (WWE) in May 2002. It would also be the only Vengeance held before the introduction of the brand extension in March 2002.

Championship unification is the act of combining two or more separate professional wrestling championships into a single title.