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From movie to TV sets, there are always a bunch of different personalities among Hollywood stars — and sometimes they just don't mix well. 

Between stars apparently refusing to act opposite one another to tension being felt even among their co-stars, fans might be shocked to learn about the behind-the-scenes drama that happened when the cameras weren't rolling. 

Here's a look at some celebs who reportedly didn't get along during their time working together: 

Emmy Rossum and Emma Kenney

Emma Kenney (right) said that her 'Shameless' co-star Emmy Rossum (left) made her feel 'anxious.' (Getty Images)

Despite playing sisters on-screen, "Shameless" stars Emmy Rossum and Emma Kenney had a tense relationship.

During a recent appearance on the "Call Her Daddy" podcast, Kenney revealed that Rossum, now 35, made her "anxious" when she was on the set.

"If she had a bad day, she made it a bad day for everybody," she added.

Kenney, 22, explained that Rossum would swap between being a "good influence" to offering up "not the best advice."

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"Growing up I definitely took a note from — not just her in particular — but people and things that I want to carry on in my life and things I do not want to carry on in my life," the "Conners" star explained.

The tension between the two came from a sense of competition between them, Kenney said, though she wasn't sure whether it stemmed from Rossum herself, or if it was fueled by others. She's certain, however, that she "wasn't creating it."

Katherine Heigl and Isaiah Washington

Katherine Heigl (left) and Isaiah Washington feuded over Washington's alleged use of a gay slur. (Getty Images)

Former "Grey's Anatomy" co-stars Katherine Heigl and Isaiah Washington seemed to have had a tense relationship in the past.

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A feud developed between the two in 2007 when Heigl, now 42, called out Washington after he allegedly called their co-star T.R. Knight "a fa---t."

Washington, 58, denied the allegations to Access Hollywood at the time, per People, but his co-star felt differently.

"I’m going to be really honest right now, he needs to just not speak in public. Period," said Heigl, who played Dr. Izzie Stevens on the medical drama's first six seasons.

Nearly 14 years later, Washington reignited the reported feud on social media, though his reasons for speaking out are unclear.

Alongside an image of Heigl, Washington tweeted: "This woman once proclaimed that I should ‘never’ be allowed to speak publicly again. The world agreed with her proclamation back then and protested for my job and my head in 65 languages. I wish I was on Twitter in 2007, because I will NEVER stop exercising my free speech."

In the comments, the actor also claimed that their co-star Chandra Wilson "knows all about that too" and when asked why he brought up the drama all these years later, Washington said, "Because it's the TRUTH. The End."

Isaiah Washington and Katherine Heigl during The Los Angeles Free Clinic's 29th Annual Dinner Gala circa 2005. (J.Sciulli/WireImage)

Meanwhile, a source close to Heigl maintained to Fox News that "Katherine stood up for her close friend twice when Isaiah publicly outed him and called him a f----t. That’s hate talk, not free speech. She is proud that she stood up for him. Katherine is and always will be an advocate and ally to LGBTQ community."

Heigl also once claimed in an interview with Entertainment Weekly that Washington apologized to her on set over the feud.

"Isaiah thanked me, which I didn't understand," she told the outlet. "He was almost grateful. I don't know Isaiah well, but he takes his work seriously and he loves his character."

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Washington exited the show after Season 3 following the accusation. While speaking about his departure on the Fox Nation series "Isaiah Washington: Kitchen Talk," he explained why he decided to publicly apologize for the incident.

"The story was a lie and misconstrued. But as a family guy, a father, I thought I was helping the family," said Washington.

He also said he wouldn't ever apologize for it again.

"That's why I'll never apologize again -- to this day," said Washington. "That's why Trump doesn't apologize, because when you apologize for something, then that it is admitted to wrong -- doing something wrong. I did nothing wrong."

Tom Hardy and Charlize Theron

The two actors were famously embroiled in a feud while on the set of "Mad Max: Fury Road," with Charlize Theron, 46, even speaking about it publicly in 2015, telling Esquire at the time that she and Tom Hardy, 44, "f---in' went at it." 

The pair's co-star Rosie Huntington-Whiteley recently said it was the differences between the stars' approaches that led to "tension."

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"There was a lot of tension, and a lot of different personalities and clashes at times," Huntington-Whiteley, 34, told The New York Times last year. "It was definitely interesting to sit in a truck for four months with Tom and Charlize, who have completely different approaches to their craft."

Meanwhile, Theron explained to the Times that, at the time, she wasn't taking into consideration the pressure that was placed on Hardy to play such an iconic character, Max Rockatansky, who had been played by Mel Gibson in several films beforehand.

Charlize Theron and Tom Hardy in "Mad Max: Fury Road." (Warner Bros. Pictures)

"In retrospect, I didn’t have enough empathy to really, truly understand what he must have felt like to step into Mel Gibson’s shoes. That is frightening," Theron said. "And I think because of my own fear, we were putting up walls to protect ourselves instead of saying to each other, 'This is scary for you, and it’s scary for me, too. Let’s be nice to each other.'"

She added: "In a weird way, we were functioning like our characters: Everything was about survival."

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Hardy agreed.

"I think in hindsight, I was in over my head in many ways. The pressure on both of us was overwhelming at times," he told the outlet. "What she needed was a better, perhaps more experienced, partner in me. That’s something that can’t be faked. I’d like to think that now that I’m older and uglier, I could rise to that occasion."

Dwayne "The Rock" Johnson and Tyrese Gibson 

Dwayne "The Rock" Johnson and Tyrese Gibson filmed installments of the "Fast & Furious" franchise together.  (Getty Images)

In 2017, reports swirled about a rift between Dwayne "The Rock" Johnson and Tyrese Gibson after rumors came out that Johnson was being tapped to do a "Fast & Furious" spinoff based on his character, Lucas Hobbs, pushing back the release date of "Fast 9," according to People magazine

Gibson, who plays Roman Pearce, even took to social media at the time, issuing an ultimatum to no one in particular, saying he wouldn't appear in the ninth installment of the franchise if the former wrestler signed on.

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However, per People, the pair's feud appeared to calm down when Johnson, 49, went into production on "Hobbs & Shaw." And in a 2018 interview with TMZ, Gibson, 42, admitted it was "not professional" and "not cool" for airing out his and Johnson's feud publicly. 

But then, according to People, in November 2019, Gibson appeared to reignite the feud after the spinoff premiered in August of that year, calling the movie – in a since-deleted social media post – "not a win." 

People reported the film's debut had the lowest box office numbers in the franchise since the third movie was released in 2006. 

Sarah Jessica Parker and Kim Cattrall

Sarah Jessica Parker starred as Carrie Bradshaw, while Kim Cattrall starred as Samantha Jones in the TV series "Sex and the City." (Getty Images)

A long-rumored feud has marred former "Sex and the City" co-stars Sarah Jessica Parker and Kim Cattrall for quite some time. 

But in October 2017 things started to become public when Cattrall revealed to Piers Morgan that she never developed a close relationship with her co-stars — Parker (Carrie Bradshaw), Kristin Davis (Charlotte York) and Cynthia Nixon (Miranda Hobbes).

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"We’ve never been friends," Cattrall, who starred as Samantha Jones on the HBO series, said at the time. "We’ve been colleagues and in some ways, it’s a very healthy place to be because then you have a clear line between your professional life and relationship and your persona."

"They all have children and I am 10 years older and since the series ended, I have been spending most of my time outside of New York so I don’t see them," Cattrall explained. "The common ground that we had was the series, and the series is over."

Actresses (L-R) Kristin Davis, Sarah Jessica Parker, Cynthia Nixon and Kim Cattrall arrive for the German premiere of ''Sex And The City: The Movie'' at a cinema in Berlin May 15, 2008. REUTERS/Fabrizio Bensch (GERMANY) - GM1E45G0BGS02

"Sex and the City" former co-stars from left to right: Kristin Davis, Sarah Jessica Parker, Cynthia Nixon and Kim Cattrall. (Reuters)

The 65-year-old actress also said she turned down the chance of portraying Samantha in the rumored "Sex and the City 3" movie.

"Not for me," Cattrall said. "That was part of turning 60... I feel that the show is the best when it was the series and the bonus was the two movies. I haven’t killed Samantha. I have released Samantha."

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Following Cattrall's interview, Parker, 56, told Andy Cohen during an appearance on his show "Watch What Happens Live" in February 2018 that she found it "upsetting" that Cattrall felt that way despite working together on the show for years.

"I found it very upsetting because that’s not the way I recall our experience," Parker said.

Just days after Parker's comments, the war of words became a bit more public when Cattrall announced the untimely death of her brother on social media. Parker was the first "Sex and the City" actress to comment on the post, sharing a brief note of condolence with Cattrall.

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"Dearest Kim, my love and condolences to you and yours and Godspeed to your beloved brother," she wrote at the time. Not long after, Cattrall posted a response to Parker’s condolence message.

"I don’t need your love or support at this tragic time @sarahjessicaparker," she wrote in a text image.

The caption continued: "My mom asked me today ‘When will that Sarah Jessica Parker, that hypocrite, leave you alone?’ Your continuous reaching out is a painful reminder of how cruel you really were then and now. Let me make this VERY clear. (If I haven’t already)."

Actresses Kim Cattrall (L) and Sarah Jessica Parker arrive for the world premiere of ''Sex And The City: The Movie'' at Leicester Square in London May 12, 2008. REUTERS/Toby Melville (BRITAIN) - GM1E45D0CCX01

Kim Cattrall and Sarah Jessica Parker sparked a very public feud. (Reuters)

"You are not my family. You are not my friend. So I’m writing to tell you one last time to stop exploiting our tragedy in order to restore your ‘nice girl’ persona."

Fast-forward to October 2018, and Parker addressed the rumored feud between the two women in an interview with Extra, saying: "If one more person calls this a catfight... I’m not in a fight. I never fought with Kim. I don’t have to send any gifts to Kim, because I’ve never done anything."

"She has felt perfectly comfortable to say lots of things – that’s the beauty of living in a democracy – but I have no apologies, meaning, this isn’t a catfight," Parker continued.

"This is someone who chose to talk about something and myself, I remain grateful for her work and the role she played on and off camera for all the years we spent together."

Mariah Carey and Nicki Minaj

Mariah Carey and Nicki Minaj were judges on "American Idol." (Getty Images)

Nicki Minaj and Mariah Carey memorably bickered throughout their time on "American Idol" for Season 12, which started with the auditions. 

In October 2012, TMZ released footage of Minaj, 38, seemingly shading Carey, 52, reportedly during auditions of the show in Charlotte, North Carolina. 

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"I told them I'm not f----n' putting up with her f----n' highness over there," Minaj says in the video. 

However, according to People magazine, in January 2013, the ladies appeared cordial during a panel promoting the reality singing competition series ahead of its season premiere. 

"The whole thing is convoluted," Carey said at the time. "It’s a distraction from the show. It’s a distraction to the contestants. It should be about the contestants."

Selma Blair and Charlie Sheen

Selma Blair and Charlie Sheen' appeared in the TV series "Anger Management" together. (Getty)

Selma Blair was reportedly fired by her "Anger Management" co-star Charlie Sheen in 2013 after she allegedly complained about the actor's work ethic.

At the time, Deadline reported that Sheen, 56, sent Blair, 49, a text message, in which he allegedly called her a "c---" before delivering the news the show was getting rid of her.

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Blair's exit was later confirmed when Lionsgate TV studio released a statement saying: "We are confirming that Selma Blair will not be returning to Anger Management and we wish her the very best."

Before her departure, Blair reportedly got on Sheen’s bad side when news spread that she was allegedly complaining about having to work with the actor, citing his tardiness and unpreparedness, according to TMZ

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Producers apparently tried to see if the issue could be resolved, however, Sheen allegedly became adamant he would quit if Blair was not axed, TMZ previously reported. 

Blair played the therapist to Sheen's Charlie Goodson on the show, which reportedly was not recast. Meanwhile, Blair tweeted a message at the time thanking her social media followers for their "support and love."

Jennie Garth and Shannen Doherty

Jennie Garth starred as Kelly Taylor, while Shannen Doherty starred as Brenda Walsh in the '90s show "Beverly Hills, 90210." (Getty Images)

"Beverly Hills, 90210" co-stars Jennie Garth and Shannen Doherty found themselves at odds while filming the hit '90s series, in which the two played frenemies Kelly Taylor (Garth) and Brenda Walsh (Doherty). 

In her 2014 book, "Deep Thoughts From a Hollywood Blonde," Garth reflected on the on-set drama, writing: "We were locked in this sound stage for 14-16 hours every day. There were times when we loved each other and there were times when we wanted to claw each other's eyes out," according to People magazine

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The 49-year-old further explained in her book why she and Doherty, 50, were at opposite ends, writing: "It was more of just young girls finding their way and finding their individual voices," Garth said, according to E! News. "Shannen and I are both Aries women, we're both very strong, independent women, so we butt heads a lot. Now, as grown women, we happen to get along as well."

It is, in fact, water under the bridge for the women as they have since gone on to appear in CW’s reboot of the show, "90210," as well as star in FOX's "BH90210." 

Freddie Prinze Jr. and Kiefer Sutherland 

Freddie Prinze Jr. and Kiefer Sutherland starred in "24." (Getty Images)

Freddie Prinze Jr. apparently had a tough time working with his "24" co-star Kiefer Sutherland so much so that he almost quit acting over Sutherland's "unprofessional" behavior.

"I did '24,' it was terrible. I hated every moment of it," Prinze, 45, told ABC News in a 2014 interview. "Kiefer was the most unprofessional dude in the world. That's not me talking trash, I'd say it to his face, I think everyone that's worked with him has said that."

"I just wanted to quit the business after that. So, I just sort of stopped," added Prinze, who appeared as Cole Ortiz alongside Sutherland's Jack Bauer on the series in 2010. 

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However, the feeling wasn't mutual, according to a rep for Sutherland, 54. "Kiefer worked with Freddie Prinze, Jr. more than five years ago, and this is the first he has heard of Freddie‘s grievances," Sutherland's rep said shortly after Prinze's interview.

"Kiefer enjoyed working with Freddie and wishes him the best," the statement added. 

Sutherland also had nothing but kind words for Prinze in 2009.

"We have some great actors joining us — Mykelti Williamson is the head of CTU, Freddie Prinze Jr. is playing my partner," Sutherland said in an interview with Parade for Season 8. "So, it's this great balance between something that’s new and what fans will find familiar."

Fox News' Tyler McCarthy and Melissa Roberto contributed to this report.