National Lampoon's Van Wilder (also known as Van Wilder: Party Liaison in certain countries) is a 2002 romantic comedy film directed by Walt Becker in his directional debut and written by Brent Goldberg and David T. Wagner. The film stars Ryan Reynolds as the title character, alongside Tara Reid, Tim Matheson, and Paul Gleason.

The film follows the misadventures of its lead character, Van Wilder, a seventh-year senior who has made it his life goal to help undergrads at Coolidge College succeed in the future. After an article is written about his legacy by fellow student, Gwen Pearson (played by Reid), Van Wilder's party lifestyle is brought to light. This attracts the attention of Wilder's father, played by Matheson, who cuts off his tuition. Wilder becomes stuck in the middle of a love triangle between Gwen and her mean-spirited boyfriend, Richard Bagg while struggling to graduate. He tries various schemes to earn enough money to pay his tuition and graduate, with help from Gwen and the rest of the student body, except for a couple of sinister enemies who attempt to sabotage his efforts.

The film received mostly negative reviews from critics but was popular with audiences. The film grossed $21,305,259 at the US box office; $16,970,224 at the international box office; and $38,275,483 overall, thus making it a box-office success.

A sequel, Van Wilder: The Rise of Taj, was released on December 1, 2006. A prequel, Van Wilder: Freshman Year, was released straight-to-DVD on July 14, 2009.

The movie was loosely inspired by a Rolling Stone article featuring comedian Bert Kreischer.