TV stars who find themselves in a hit show are in a tricky situation. It's not like with movies where they can line up lots of different projects – you're kinda stuck in the same routine for years.

But what do you do? Risk sticking around and regret the lost opportunities or quit and regret losing an amazing gig? While leaving can sometimes end up being a great career move, it can also be a massive facepalm.

So whether it's down to on-set disputes or knee-jerk decision-making, here are eight stars who didn't know what they'd got till it was gone.

1. Christopher Eccleston (Doctor Who)

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We were always a bit peeved that Christopher didn't stick around for more than a single season of Doctor Who after 2005's big revival, and that he didn't come back for the 50th anniversary either.

But he has at least acknowledged pangs of regret over leaving so early, telling 774 ABC Melbourne's Drive radio show last year: "There's always regret [to not continue] when you play a role like that because… I watched it back and I thought 'Okay, don't do this, do that, calibrate the performance'.

"It was kinda tragic for me that I didn't play him for longer. He's a beautiful character. I have a great deal of professional pride and, had I done a second season, there would've been a marked improvement in my performance. I was learning new skills in terms of playing light comedy. I was not known for light comedy and, again, production did not allow for that."

2. Katherine Heigl (Grey's Anatomy)

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Katherine was one of the breakout stars of ABC's hit medical drama as Dr Izzie Stevens, a role she played for five seasons, until she was alleged to have stopped showing up for work during the sixth season. She and creator Shonda Rhimes came to an agreement to terminate her contract immediately, and her quest to be a Hollywood leading lady began (and ended shortly afterwards).

Speaking to the Wall Street Journal in 2014, she admitted that she wished she'd handled the situation differently, though didn't go as far to say that she regretted leaving altogether.

She said: "There's certainly things I regret about it, but at the end of the day – I don't know when I came to this conclusion, maybe like in the last year or so – I realised I don't regret the decision. It was the right decision for me to make at the time. Because I made that decision, I did right by my husband, my children, myself."

3. Brian Dunkleman (American Idol)

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It's not just actors who regret leaving their hit shows, just ask poor Brian Dunkleman. Who, you ask? He was the co-host of American Idol's first season with Ryan Seacrest. Yes, it originally had two hosts.

So while Seacrest has become a huge entertainment star in the US, like a one-man Ant & Dec, Brian is kinda... not. Instead, he decided to quit after just one season and hasn't quite found success since, aside from small roles and voice work.

"I wanted to have an acting career, and I knew that leaving when I did would give me the best shot of accomplishing that," he wrote for Variety. "Do I regret not remaining on the show now that it's coming to an end? Yes. Especially when I open my bank statements."

He did at least return for the show's finale, appearing on stage one last time with Seacrest. And it wasn't awkward at all.

4. Thomas Gibson (Criminal Minds)

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You'd think someone who got fired from their own show for reportedly kicking someone's shins on the set would not be enormously peeved that they had to leave.

As Aaron 'Hotch' Hotchner, Gibson was the lead for 11 seasons (apart from the time he had to get anger management therapy after pushing a producer), but after just two episodes of the 12th, he was dismissed after allegedly kicking a writer during a dispute over the script (Gibson says "choice words" were exchanged during the dispute and "my foot came up and tapped him on the leg"). But he felt bad about it – because his character didn't get the send-off he deserved.

"There were creative differences on the set and a disagreement," Gibson admitted in a statement at the time. "I regret that it occurred. I love Criminal Minds and have put my heart and soul into it for the last 12 years.

"I had hoped to see it through to the end, but that won't be possible now. I would just like to say thank you to the writers, producers, actors, our amazing crew, and, most importantly, the best fans that a show could ever hope to have."

5. Ben Miller (Death in Paradise)

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After three series of solving cases in sunny climates, Ben Miller suddenly quit the BBC series, and was killed off in the process. Cue Kris Marshall as his replacement Humph. That's not us being annoyed, that's his name.

While Ben has never technically said that he wishes he never left the show, he's made it quite clear that he misses it (and the hot weather), and that his departure was due to his wanting to spend time with his growing family.

Speaking to Digital Spy last summer, Ben told us in a somewhat wistful manner: "On balance, I think it was the right decision. It was a difficult thing to go through, it was a hard thing to see a character you love killed. And in a particularly brutal fashion! Not that anyone in Death in Paradise dies in a gentle way, they're always quite extreme!

"I loved the hot sun, but what wasn't quite so practical was that I'd been out there barely two weeks when I discovered my wife was pregnant, so that was the difficulty for me."

He added to Radio Times: "I do still miss Guadeloupe it's such an amazing, beautiful place. How lucky am I to go to those two incredible places to film?"

6. Bill Turnbull (BBC Breakfast)

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After 15 years of sitting on the comfy BBC Breakfast sofa, Bill decided to leave the show after turning 60. And despite looking forward to lie-ins, he has since revealed that he misses the early starts.

"When 60 came around I would have been presenting the programme for 15 years and I thought 'That's enough time' and it's better to go while people want you to stay than stay when people want you to go," he told the Express.

"Having said that, given everything that's happened in the world since I left, I almost wish I'd stayed for another year. I wouldn't suggest replacing Dan Walker ever, he's done a great job.

"But, for me, when I was building up for leaving nothing had really happened in news for a while, there was the odd story, then all of a sudden, boom, everything rose up! The most unlikely things; the Brexit vote, Donald Trump getting elected and Ed Balls in Strictly Come Dancing."

7. Matt Smith (Doctor Who)

Okay, this is a bit of a cheeky one: Matt didn't exactly say that he wishes he never left Doctor Who, but rather that he wished he'd starred opposite Jenna Coleman's Clara for a bit longer.

"That's one of my great regrets, that I didn't get a full season with Jenna," he said at a panel at New York Comic-Con last year.

Back in July 2016, tabloid reports suggested that Smith was being lined up for a return to Doctor Who, though he later shot down the rumours.

"It's Peter [Capaldi]'s TARDIS now. And I love what he does. So I watch as a fan."

It's not even Peter's now…

8. Dave Chappelle (Chappelle's Show)

Dave Chappelle's Comedy Central series was one of the most popular and credible sketch shows back in 2003, but it sadly only lasted for two seasons. This was down to Chappelle abruptly quitting the series, turning his back on a deal for two more runs for an alleged $50 million and jetting off to South Africa.

He finally spoke about the affair with David Letterman in 2014, offering feelings of regret for not doing more when his career was peaking. "I felt a variety of ways in the last 10 years," he said. "There's nothing anyone can say. You do what you feel like you need to do at any given time."

He continued: "You know, whenever there's something that I'd like to have that I could have afforded that I can't now afford, well, then I'm upset about it. But then when I see a guy going to do a job that's time consuming and he doesn't have the free time to do things that I get to do, then I feel good about it.

"But, overall, in your heart, in everyone's heart, we know money is not the answer or the solution," Letterman pointed out. "And let's just say you had the $40 million, who is to say you would be a happier or better person?"

We can all answer that for ourselves, in our own, quiet way.

From: Digital Spy