October 3, 2004 — This Friday’s release of "Stage Beauty," starring Billy Crudup and Claire Danes, is notorious for its back story: Crudup dumped his heavily pregnant wife, Mary Louise Parker, after he hooked up with Danes while shooting the movie last year. But despite all the raised eyebrows, this couple was only following a long tradition: the irresistible temptation to fool around with one’s co-star (or, in some cases, with the help). Here are some Hollywood highlights:

On the set of the 2003 vampire action flick "Underworld," sexy Kate Beckinsale ditched co-star husband Michael Sheen (with whom she had a 2-year-old daughter, Lily) after falling for handsome young director Len Wiseman.

Beckinsale has said of new sweetheart Wiseman, whom she married in May, "We agree on pretty much everything." Presumably, that includes not casting jilted hubby Sheen in the "Underworld" sequel.

It’s Bennifer II, as Ben Affleck follows his tabloid-tornado breakup with J.Lo with another high-profile conquest - "Daredevil" co-star Jennifer Garner. The brand new Ben and Jen met in 2001 shooting "Pearl Harbor" and began "formally" dating this year - but even a blind man could see their chemistry.

Jude Law’s been a busy boy lately. He’s recently divorced, has six movies out this year and is in a blooming romance with nubile "Alfie" co-star Sienna Miller. She has apparently been helping to soothe the hard-working heartthrob after his painful split from actress-producer Sadie Frost, 37. (Maybe he can replace his "Sexy Sadie" tattoo with one saying, "It’s Miller Time.")

Russell Crowe enjoys his wine, women and song - and for that, the brutish Aussie actor is a regular on the supermarket tabloid rack. Back in 1999, before the now-married Crowe said "I do" to longtime sweetheart Danielle Spencer, he and cutesy co-star Meg Ryan had a not-so-top-secret dalliance on the set of the guerrilla rescue-mission movie "Proof of Life."

Ryan and actor husband Dennis Quaid - with whom she had a 7-year-old son at the time - were divorced in September 2001.

How’s this for a convoluted plot? The "girlfriend" character Matt Damon penned into the Oscar-winning screenplay of 1997’s "Good Will Hunting" was named Skylar - after his old girlfriend at Harvard - and played by Minnie Driver, who became his new girlfriend after sparks flew on the set.

How’s this for an even stranger denouement? Damon informed the world, and a stunned Driver, that they were kaput during an interview on "The Oprah Winfrey Show." As for the real-life Skylar - she became an ER doctor and married Metallica drummer Lars Ulrich (though they recently filed for divorce).

In a reverse "Pretty Woman" story, lowly cameraman Danny Moder wooed mega-star Julia Roberts on the set of her 2001 film "The Mexican." The only major snag with this fairy tale was the little matter of the cameraman’s makeup-artist wife, Vera.

Sarah Michelle Gellar and Freddie Prinze Jr. found each other while filming 1997’s "I Know What You Did Last Summer," and now seven years - and two "Scooby-Doo" movies - later, they’re happily married.