There's Something About Mary is an American film released in 1998 by 20th Century Fox, directed by Bobby Farrelly and Peter Farrelly (the Farrelly brothers). A combination of romantic comedy and gross-out film, it stars Ben Stiller, Cameron Diaz, Matt Dillon, Chris Elliott, Lin Shaye, W. Earl Brown, Lee Evans and Jeffrey Tambor, with cameo appearances by football star Brett Favre (who plays himself), Sarah Silverman, Keith David, and Harland Williams.

This sleeper hit was the third-highest-grossing movie of 1998 in North America—the highest-grossing comedy—and it catapulted Stiller into the limelight. Until Wedding Crashers was released in 2005, There's Something About Mary was the most successful youth-aimed R-rated comedy film at the box office.

There's Something About Mary was placed 27th in the American Film Institute's 100 Years, 100 Laughs: America's Funniest Movies (see the 100 Years Series), a list of the 100 funniest movies of the 20th century. In 2000, readers of Total Film magazine voted it the 4th greatest comedy film of all time. This film is number 4 on Bravo's "100 Funniest Movies".

The movie has made $176 million in the U.S. alone and 369 million worldwide.

An awkward and shy high-schooler, Ted (Ben Stiller) lands a prom date with his dream girl Mary (Cameron Diaz), just to have it cut short by a painfully humiliating zipper accident. Thirteen years later he's still in love—maybe even obsessed—with the one that got away, so he hires sleazy private detective Pat Healy (Matt Dillon) to track her down living in Miami, only to have Pat fall for the irresistible Mary as well. Ted and Pat resort to lying, cheating and stalking in their competition for Mary (Pat tries to dissuade Ted by telling him that Mary has grown unattractive), and discover that they're not the only men (or women) who will use depraved measures to be near her. In the end, Mary chooses Ted.

The movie's over-the-top and sometimes disturbing gross-out humor earned it an R rating from the MPAA, but made it a smash hit at the box office. The most notorious scene features Stiller's character masturbating and losing track of his ejaculate. Diaz's character notices it clinging to his ear, mistakes it for extra hair gel, and spreads it in her own hair. The "hair gel" scene spread by word of mouth, and later ads for the movie capitalized on its notoriety.