Michael Strahan's abrupt exit from Live! With Kelly and Michael certainly won't improve his relationship with co-host Kelly Ripa.
While the 44-year-old former NFL pro thanked Ripa, 45, during Wednesday's show -- an episode from which Ripa was absent after feeling "blindsided" by Strahan's announcement -- sources told ET it wasn't all love between the morning show hosts.
"Michael and Kelly have not been getting along recently," one source said. "They got along great in the beginning, but not so much lately."
It's not the first time and it won't be the last that co-stars haven't gotten along on set. Here are eight other examples of stars who were beefing behind the scenes.
1. Nathan Fillion & Stana Katic
Castle fans and co-stars alike were shocked when word broke that Katic would not be returning for the ABC drama's ninth season. Though Fillion said she would be missed, a source tells ET the stars wouldn’t even speak to each other on set. It got so bad that the two were reportedly sent to "couples therapy."
The Mad Max: Fury Road actress told Esquire she and Hardy "f**kin' went at it...We drove each other crazy" and later said, "From what I hear, he's not like that on every movie -- I hear he's had good experiences." Meanwhile, Theron also said she had a "rough time" with Maguire while filming Cider House Rules, telling V magazine, "We're good now. It was a difficult movie..."
3. Cheryl Burke & Ian Ziering
The Dancing With the Stars pro revealed on the Allegedly podcast that Ziering was her "least favorite" partner and, when asked if it made her want to leave the show, she said, "No, but it made me want to slit my wrists." Burke later said her reference to suicide were "out of line." She added, "I've always lived by the rule that if you don't have anything nice to say, don't say anything at all...Regrettably, I broke that rule."
Filming The Notebook wasn't all, "If you're a bird, I'm a bird." Gosling reportedly called McAdams -- who he would later go on to date -- "difficult to work with" and "uncooperative" and director Nick Cassavetes said the actor even tried to get McAdams kicked off the film. "They were really not getting along one day on set. Really not," he said.
5. Mariah Carey & Nicki Minaj
Both divas joined the American Idol judging panel in 2013 and things quickly escalated on camera and off. Minaj blasted Carey as "insecure" and "bitter" on Twitter, while Carey called her time on Idol"the worst experience of my life" and likened it to "going to work every day in hell with Satan." We have a feeling Ryan Seacrest was not Satan in that scenario.
6. Alex Pettyfer and Channing Tatum
Pettyfer was absent from Magic Mike XXL and claimed it was "because Channing Tatum does not like me." The actor revealed on a podcast that he rented an apartment from Channing's friend, but didn't pay his rent. According to Pettyfer, "I got a very negative email from Channing, saying, 'Don't f**k my friends. You owe money. Pay the f**king money. Don't be a clown.'"
Garth wrote in her memoir, Deep Thoughts From a Hollywood Blonde, that she and Doherty were "bitter rivals" and like "gasoline and a match" on Beverly Hills, 90210 -- never coming to blows but getting "very, very close." Doherty left the show and went on to star in Charmed, where Milano admitted the two had "rough days." Doherty simply told ET of her exit, "There was too much drama on that set."
8. Patrick Swayze & Jennifer Grey
They may have portrayed one of the greatest romances of all time, but Swayze and Grey apparently did not feel the love while shooting Dirty Dancing. In his autobiography, The Time of My Life, the actor wrote, "We did have a few moments of friction." Swayze added that his co-star was "particularly emotional" and prone to "silly moods."
But hey, in the end, he said Grey did a "truly phenomenal job." So, that's nice!
Speaking of old feuds, Katherine Heigl admits she should've "shut up" about that whole Grey's Anatomy Emmy debacle. Find out what she had to say in the video below.