Rumors continue to fly that Katherine Heigl is unhappy on "Grey's Anatomy" and has one foot out the door (which the show's writers are probably happy to hold open after Heigl's slam on them last year, when she took her name out of Emmy consideration because she felt her storyline wasn't strong enough). And while Katherine thinks she's poised for a big film career, we offer her these two words of caution: David Caruso.

Remember, Katherine, there are a lot of beautiful actresses who could have played your part in "Knocked Up," and your star turn in "27 Dresses" was NOT an instant classic. We suggest you think long and hard before walking away from the show that made you famous.

We recommend that you take a look at these other stars who left their hit shows and see where it got them. Then start praying that the writers forgive you and find a cure for Izzy's cancer.

PHOTOS: See the stars who left hit TV shows.

David Caruso

In perhaps the most notorious, ego-driven prime-time exit ever, David Caruso left "NYPD Blue" after the first season because he wanted to focus on his film career. What followed were the flops "Jade" and the aptly named "Kiss of Death." With his tail between his legs but his head held high (and, of course, adorned with sunglasses), Caruso finally found success once again by returning to the small screen with the hit show "CSI: Miami." This time, he's been smart enough to stick around for seven seasons and counting.

Delta Burke

Delta Burke played the ex-beauty pageant queen Suzanne Sugarbaker on "Designing Women" for five seasons. But as the series progressed, Delta started to gain a little weight. What happened next will forever be a case of he-said/she-said. Delta says the show's producers started to pressure her to lose weight. Producers say they didn't care but were bothered by Delta's public statements to Barbara Walters that they were unhappy with her appearance. But no matter how you slice it, Delta left the show. She and "DW" creator Linda Bloodworth-Thomason would make up a few years later for a delayed spinoff called "Women of the House." But that show lasted just one season, and Delta would never be as big a star (no pun intended) again.

Courtney Thorne-Smith

Like Delta Burke, Courtney Thorne-Smith asked to get out of her "Ally McBeal" contract at the end of the third season because of weight issues. But Courtney's problem was that she was getting too thin. Trying to keep up with waiflike costars Calista Flockhart and Portia de Rossi meant that Thorne was dieting too much, working out too hard, and pushing herself to exhaustion. So she chose health (and husband) over stardom, and left the show at its peak. She and her next costar, Jim Belushi, were much less competitive about their weight on "According to Jim."

Chevy Chase

In perhaps the lamest-ever reason for leaving a hit show, Chevy Chase quit "Saturday Night Live" at the beginning of the second season for a girl who lived in Los Angeles. Jacqueline Carlin did marry Chevy (she was his second wife), but they divorced four years later. "SNL" celebrates its 34th anniversary this year. You do the math.

Farrah Fawcett

Whether Farrah Fawcett quit the hit TV show "Charlie's Angels" because she thought the scripts were too lightweight and she wanted to be a movie star or because her then-husband, Lee Majors, wanted her home to cook dinner every night is still open for debate. But one thing's for sure — neither turned out to be a good reason to go. America's favorite poster girl never landed that credible feature film role and aside from the TV flick "The Burning Bed," she never had much success on the small screen again either. As for Majors, she left him a few years later to cook dinner for his best friend, Ryan O'Neal, who she's lived with on and off ever since.

Sherry Stringfield

Sherry Stringfield has left so many shows too soon that she's known as the "Goodbye Girl" in Hollywood circles. First there was the daytime soap opera "Guiding Light." Sherry spent three years there before she must have realized she missed everyone else's post-college trip, so she quit the show to spend a year traveling around Europe. When she got back, she landed a choice role on "NYPD Blue" as the ex-wife of fellow hit show bolter David Caruso. This time she just wasn't satisfied with her experience and was released from her contract early. Then came the mother of all hit shows you shouldn't leave: "ER." Stringfield was riding high, as producer John Wells had just introduced a romantic storyline between Sherry and Anthony Edwards. But she pulled a runaway actress move yet again, this time, she said, to have a normal life with boyfriend Odell Lambroza and get away from the grueling schedule of network TV. She ended up with lots of time on her hands before returning to "ER" in 2001. She and Lambroza broke up one year after she quit the show to be with him.

Wayne Rogers

When Wayne Rogers signed up for "M*A*S*H" he thought he was going to take over the juicy part created by Elliott Gould in the feature film version. But instead, he became Hawkeye Pierce's sidekick. He wasn't pleased. To add insult to injury, producers put a morals clause in his contract that stated that they could fire him if they didn't like his off-screen behavior. As a result, Wayne quit the show and was sued for breach of contract. The only problem? He never signed the contract to begin with. Wayne later expressed regret for leaving the show when he did, saying if he knew how long the series would last he would have sucked it up, shut his mouth, and stuck around.

Shelley Long

Diane Chambers was not the best-liked person at the Cheers bar. The snooty ex-grad student and would-be author was just a little too pretentious for regular barflies Norm and Cliff. It took Sam Malone a long time to warm up to her. And no-nonsense barmaid Carla Tortelli never liked her. In a case of life imitating art, the story goes that no one really liked Shelley Long that much either. So there probably weren't a lot of people crying in their beers when Diane left Sam at the barstool/altar to finish her novel. But we're sure Shelley could have used a few drinks after seeing the reviews for her "Cheers" follow-ups, the disastrously disappointing films "Hello Again" and "Troop Beverly Hills."

Shannen Doherty

After four years at West Beverly High, Brenda Walsh graduated and moved back to Minnesota to go to college. At least that's what the writers said to explain the absence of "Beverly Hills, 90210" star Shannen Doherty. In real life, everyone says Shannen was tardy a lot and didn't play well with others. Not the report card for a successful career in an ensemble cast. Shannen went off, got into a bar fight, allegedly trashed a rental house, married George Hamilton's son Ashley just two weeks after meeting him, and split-up with Ashley two years later... oh, and she had her obligatory stint in "Playboy" too. But no one seemed to care much about her until she returned to the remake of "90210" this season. It seems you can go back home again.

Gabe Kaplan

At the end of Season 3 of "Welcome Back, Kotter" everyone expected that John Travolta would leave the show — he was the break-out star and had a hit movie with "Saturday Night Fever." No one expected that Gabe Kaplan, aka Mr. Kotter, would decide to split too. After all, he was the title character, and he'd created the series based on his own childhood friends. But creative differences with producer James Komack were more than Gabe could take, so he decided to pack it in and go back to stand-up comedy. He made only a handful of appearances in the fourth and final season of the series and has barely been seen on TV or in movies since. But don't cry for Mr. Koh-ter; he's now a professional poker player whose tournament winnings total over $1.3 million as of 2008.

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