For 18 years,Grey's Anatomyhas been the longest-running American prime-time medical drama series.

While it's been one hell of a watch on our TV screens, there's also been quite a bit of drama behind the scenes.

What's worse is the drama has been going on since the beginning of time basically (or 2005, whenGrey's Anatomystarted streaming).

Watch: Throwback to Katherine Heigl on Grey's Anatomy. Post continues below video.

Behind-the-scenes there's been fights, an acknowledged 'toxic culture' anda lotof firings (some warranted and some... not). Here's a complete timeline.

2006-2007.

Around this time is when Isaiah Washington and T. R. Knight's drama first came to light.

Washington yelled a homophobic slur about Knight (Dr George O'Malley) at Patrick Dempsey (McDreamy, but you knew that already) during a literal on-set fist fight.

Knight came out of the closet in aPeoplemagazine story published 10 days after the incident.

Washington apologised on October 26, but in January the issue resurfaced when he repeated the word, saying "I did not call T.R. a f*****. Never happened," at the 2007 Golden Globes.

"I apologise to T.R., my colleagues, the fans of the show and especially the lesbian and gay community for using a word that is unacceptable in any context or circumstance," Washington said in a statement after the awards show. "By repeating the word Monday night, I marred what should have been a perfect night for everyone who works on Grey's Anatomy. I can neither defend nor explain my behaviour. I can also no longer deny to myself that there are issues I obviously need to examine within my own soul, and I've asked for help."

On Twitter in November 2020, Washington said he should never have apologised.

The Washington Examiner reported Heigl was "irate" with Washington's comments in the Golden Globes press room and said: "He needs to just not speak in public. Period".

"T.R. is my best friend. I will throw down for that kid. I will beat you up. I will use every ounce of energy I have to take you down if you hurt his feelings," she was reported as saying at a Globes after-party.

In June 2007, ABC announced it would not be renewing Washington's contract and he would be dropped from the show.

In a statement reacting to his axing, Washington said he was "mad as hell and I'm not going to take it anymore".

A month later in July, Washington appeared onLarry King Liveon CNN and said he never used the "F Word" in reference to Knight, but rather told Dempsey to stop treating him like a "F-word" during an argument "provoked" by Dempsey, who, he felt, was treating him like a "B-word", a "P-word", and the "F-word", which Washington said he meant to mean "somebody who is being weak".

Washington's drama got him fired - though he made a brief reappearance for Sandra Oh's (Cristina Yang) final storyline.

2008.

In 2008, Heigl pulled her name from Emmy contention despite winning an Emmy the season before.

In a statement to theLos Angeles Times, Heigl explained her decision by throwing some major shade at the show's writers.

"I did not feel that I was given the material this season to warrant an Emmy nomination, and in an effort to maintain the integrity of the academy organisation, I withdrew my name from contention," she said.

The show's writers and producers were reportedly (and understandably) pissed, but Rhimes said the reason Heigl's character was given less material than previous seasons was because she had requested a lighter schedule.

Though Izzie remained a core part of the show for season six, this Emmy debacle seemed to be the beginning of the end for Heigl's character.

2009.

In 2009, Knight announced he was leaving the show, frustrated by the lack of screen time his character George was receiving.

In an interview with Entertainment Weekly he said he did not discuss this frustration, which saw George appear in just 48 minutes in the first nine episodes of season five, with Rhimes due to a "breakdown of communication". Instead, he just decided to leave.

"My five-year experience proved to me that I could not trust any answer that was given [about George]," he explained. "And with respect, I’m going to leave it at that."

Heigl continued to be a little shady throughout 2009 and publicly complained about the show during a talk show appearance.

Heigl complained about long filming days onThe Late Show With David Letterman (even though, according to BuddyTV, she caused the long days because producers were trying to accommodate her media tour for rom-com The Ugly Truth).

"Our first day back was Wednesday and it was - I'm going to keep saying this because I hope it embarrasses them - a 17-hour day, which I think is cruel and mean."

When Letterman asked how much longer she'd be on the show she replied: "Yeah, that's what I keep wondering".

2010.

Oh, it turns out Letterman's question was very timely because within months, Heigl was on the way out.

Rumours that the actress would leaveGrey's Anatomypersisted throughout season six, partly because Heigl had not been shy about wanting to focus on her movie career.

Then, on March 11, 2010, Heigl reportedly did not show up for work... So she and Rhimes reached an agreement to immediately release her from her contract.

2012.

Two years later in 2012, show creator Shonda Rhimes was still not stoked with how things went down with Heigl.

"On some level, it stung," she toldTV Guideof Heigl's exit, "and on some level, I was not surprised. When people show you who they are, believe them."

The same year, Eric Dane (Mark Sloan, AKA McSteamy, AKA the TV death I will never recover from) was written out of the show.

He made a small dig at the show in an interview with French news outletProgramme TV, saying - according to an English translation - that onGrey'she was "just a piece of meat".

2013.

In 2013, Pompeo told theNew York Postshe understood why Heigl wanted to leave, but the scandal surrounding her exit took its toll on the cast.

"Hurt feelings, combined with instant success and huge paychecks started things spinning out of control," she said.

"It was tough. You could understand why she wanted to go - when you're offered $12 million a movie and you're only 26. But [Heigl's] problem is that she should not have renewed her contract. She re-upped, took a big raise and then tried to get off the show."

Then Pompeo couldn't resist a dig at her former co-star: "And then her movie career did not take off."

Ouch.

2014.

Washington returned toGrey's Anatomywas Oh's final episode in season 10, neatly wrapping up her storyline. But that decision copped Rhimes a lot of criticism considering he was fired seven years earlier following homophobic slurs.

"My first decision and my first responsibility is to the story. I have to be the keeper of the story and make sure that we're telling the story we need to tell, regardless of whatever outside factors are involved or whatever history is involved," Rhimes toldEntertainment Weeklyat the time, defending her decision.

"I also want to just be clear that Isaiah is a person that we all love and have loved for a very long time. I feel like there have been a lot of people that have been like, 'How can you do this?' And I feel very strongly and fully believe in people's ability to grow and change and learn from their mistakes and when they know better, to do better.

"If people don't think that, over the course of seven years, it's possible for a human being to change, then there really is no future for the human race at all."

In October 2014, Rhimes made her infamous 'no Heigls' on set policy comment toThe Hollywood Reporter.

"I don't put up with bullsh** or nasty people. I don't have time for it," she said.

A month later, Heigl responded during an appearance onExtra.

"I'm sorry that she feels that way, and I wish her nothing but greatness, and I have nothing negative to say about Shonda. I'm a big fan of her work," she said.

"I watchScandalevery week. I'm sorry she's left with such a crappy impression of me. I wish I could do something to change that. Maybe I will be able to someday."

2015.

In 2015 rumours were flying that Dempsey, AKA Dr Derek 'McDreamy' Shepherd was about to be fired.

His character was shipped off to D.C. for much of season 11 and ultimately uh... *spoiler alert* didn't make it beyond that season, despite being contracted for season 12.

On April 20, 2015 (just three days before the season 11 episode where Derek died was aired) a show source told Page Six it was down to 'diva' behaviour from the show lead.

"Patrick has been acting like a diva and has clashed with Shonda," they said. "She suspended him for a while, and the word on set is that he isn’t coming back full time."

"Given all the past problems with Katherine Heigl and Isaiah Washington, there is little tolerance on the show for troublesome talent."

In November of that year, Rhimes admitted during an appearance onThe Nightly Show With Larry Wilmorethat she has killed off a character from one of her shows because didn't personally like the actor.

She never revealed who she was talking about, but the timing was... curious.

Dempsey responded a month later to say he thought Rhimes "loves being provocative and that's fine for who she is".

"That gets people talking about all the stuff that she's doing. She's promoting a book. She's promoting three shows. I think she knows how to deal with the media and what she needs to say to get the response that she's looking for," he toldEntertainment Weekly.

In September 2021, an unauthorised book by author Lynette Rice,How To Save A Life: The Inside Story Of Grey’s Anatomy, published further details about Dempsey's departure.

In an excerpt published by the Hollywood Reporter, the book claimed he was "terrorising the set" before being written off the series.

"There were HR issues. It wasn't sexual in any way. He sort of was terrorising the set. Some cast members had all sorts of PTSD with him," executive producer James D. Parriott, who was brought back to the series to oversee Dempsey's exit, recalled.

"He had this hold on the set where he knew he could stop production and scare people. The network and studio came down, and we had sessions with them. I think he was just done with the show. He didn't like the inconvenience of coming in every day and working. He and Shonda were at each other's throats."

Producer Jeannine Renshaw recalled how Pompeo would get frustrated with her co-star.

"She would get angry that he wasn't working as much. She was very big on having things be fair. She just didn’t like that Patrick would complain that 'I'm here too late' or 'I've been here too long' when she had twice as many scenes in the episode as he did," Renshaw said.

"When I brought it up to Patrick, I would say, 'Look around you. These people have been here since 6.30 am'. He would go, 'Oh, yeah.' He would get it. It's just that actors tend to see things from their own perspective."

An unnamed cast member remembered how many of the show's cast would "go running to Shond