If there’s one thing Hollywood is never short on, it’s egos. And in an industry where collaboration is key, putting those egos in the same room (or stranding them in the desert) can sometimes produce disastrous results that range anywhere from stressful productions to full-on fisticuffs. Like combining baking soda with vinegar, here are some celebs that learned the hard way that they should probably never work together again.

Nicki Minaj and Mariah Carey

When it comes to being a diva, no one does it quite like Mariah Carey, so when American Idol producers put Carey on the judges’ panel with Nicki Minaj, they must have known the sparks would fly.

During auditions in Charlotte, N.C. in 2012, tensions exploded when Minaj hurled profanities at Carey after growing tired of "her f**kin’ highness over there." The entire back-and-forth was captured on video and leaked to TMZ, which only made matters worse because Carey’s team later claimed that Minaj said, "If I had a gun, I would shoot her." Idol producer Nigel Lythgoe told TMZ that accusation was "rubbish" and alleged Mimi’s people were "stirring the pot."

After the epic blowout died down, the two eventually went back to acting like professionals, according to People. However, in the lead-up to Idol‘s 15th season, BET reported that Carey claimed the feud was fake and cooked up by producers. Mike Darnell, Fox’s president of alternative programming, and Lythgoe made it clear to E! News that the feud was all too real and a "nightmare experience." They also know exactly who was to blame. "Nicki was not the problem," Lythgoe said.

As for the current state of Minaj and Carey’s relationship, it’s still a hot mess. According to Lainey Gossip, Carey poured "blatant" fuel on the feud by joining forces with Remy Ma (another artist who is not a Minaj fan) on a remix of "I Don’t" in 2017.

David O. Russell and George Clooney

In 1997, George Clooney was primarily known for his television role on E.R. (1994-2009), and his career in film was by no means a sure thing. So it was a pretty bold move when the TV doctor literally went toe-to-toe with director David O. Russell on the set of Three Kings (1999). In a 2000 interview with Playboy (via Clooney’s Open House), the actor claimed that he grew tired of Russell constantly berating crew members, and the situation reached a boiling point when the director allegedly kicked an extra.

According to Clooney, he approached Russell and attempted to diffuse the situation, which did not go well. After a screaming match, Russell allegedly headbutted Clooney, Clooney attacked Russell, and the two had to be physically pulled apart. "I had him by the throat," Clooney told Playboy. "I was going to kill him. Kill him." By that point, "the Warner Bros. guys were freaking out," but Russell and Clooney made it through the rest of production. However, Clooney swore he’d never work with Russell again.

Years later, the two Hollywood players still had some choice words for each other. "Quite honestly, if he comes near me, I’ll sock him right in the f**king mouth," Clooney told Premiere (via The Guardian) in 2004. As for Russell, if he ran into Clooney: "I’d say, ‘Shut the f**k up, you lying-*ss b***h.’"

Definitely keep those two apart.

Tina Fey and Paris Hilton

Tina Fey has had a long career cracking jokes about celebrities, and yet she seems to walk a fine line that keeps you in their good graces. She’s still close with Lindsay Lohan, which proves Fey can be pretty forgiving when it comes to celebrity antics. However, during Fey’s time on Saturday Night Live, Paris Hilton was apparently an absolute nightmare of a host, and Fey didn’t hold back when asked to share her thoughts on the hotel heiress. Fey referred to Hilton as a "piece of sh*t" in an interview with Howard Stern (via Gawker).

According to Fey, Hilton "embraced her stupidity" and demanded to star in a sketch as Jessica Simpson because Hilton allegedly thinks the singer is fat and hates her. Fey claimed The Simple Life star barely acknowledged the cast, and in Fey’s words, her "cheap weave" dropped "nasty wads of Barbie hair on the floor." Yikes!

Again, Fey is willing to work with Lohan, one of the most notoriously difficult actresses in Hollywood, so the fact that Hilton was a bridge too far for the SNL alum is pretty bad.

James Franco and Tyrese Gibson

While filming Annapolis (2006), co-stars James Franco and Tyrese Gibson feuded so hard that Gibson openly told Elle in 2007 that he wished he could blow up Franco’s house. According to Uproxx, the tension between the two stemmed from Franco’s method acting, which even Franco himself admits was way out of control in his early acting days.

In an interview with Playboy (via Uproxx), Gibson said he felt like it was more than just method acting when Franco refused to break character even while practicing the film’s boxing scenes, which often involved Gibson repeatedly getting punched, despite telling Franco to lighten up. "I never want to work with him again, and I’m sure he feels the same way," Gibson said. "It felt very personal. It was f**ked-up."

In his defense, Franco claims he attempted to make up with Gibson, and he takes full responsibility for the "misunderstandings," which is one way to describe repeatedly punching your co-star in the face. As for Gibson, he’s remained mum on the subject, and we don’t see the two working together again anytime soon.

Bruce Willis and Kevin Smith

In 2009, Kevin Smith took a massive pay cut for a chance to work with Bruce Willis on the buddy comedy Cop Out (2010). It was also the first time Smith directed a movie he didn’t write, but he was up for the challenge if it meant working with Willis. Unfortunately, some dreams die hard, and that’s the way it went for Scott.

On an episode of WTF With Marc Maron (via Uproxx), Smith described working with Willis as "soul crushing." He said Willis was essentially zero help and wouldn’t even sit for the movie poster. In a lengthier interview with SBS Australia, Smith said he knew from day one that Willis was completely checked out for two reasons. 1. He was supposedly intimidated by Tracy Morgan’s ad lib skills. "You could just see the colour draining out of his face," Smith said. And 2. Willis allegedly only cared about the money, which is something that Smith had not dealt with before.

"Willis was the person I worked with in my entire career who was a paycheck player," Smith said. "A straight up paycheck player. Nothing wrong with that, it’s not against the law, but if you’re going to get paid to do the job, do the job. He didn’t want to do that."

After Cop Out, Smith went back to making indie films, while Willis continued to churn out movies at a steady clip. We’re pretty sure the two are happier without each other.

Charlie Sheen and Selma Blair

In 2013, Selma Blair threatened to sue Charlie Sheen and Lionsgate for wrongful termination after she was fired from Anger Management (2012-14). According to TMZ, Blair believed Sheen had her written off the show after she complained about him holding up production by being a "slacker" who never memorized his lines.

However, sources told TMZ that Blair’s time on the show was always going to be short-lived, but when Sheen heard about her complaining, "the process was accelerated." According to Radar, that process allegedly involved Sheen firing Blair via text and calling her a certain c-word.

While Blair and Lionsgate presumably reached a settlement, Sheen was still salty about the situation in 2017. While appearing on Watch What Happens Live! (via Us Weekly), he was asked to rank his favorite female co-stars. He praised Heather Locklear and said Lohan was "fun to look at." As for Blair and Jenny McCarthy? "I’d like to mash those two together and then kick them to the curb," he said. "They deserve each other."

Kiefer Sutherland and Freddie Prinze Jr.

It’s no secret that Kiefer Sutherland loves booze. The actor has four DUIs, and he literally wrote a love song dedicated to alcohol. Basically, Jack Bauer likes to drink. On top of that, he’s also kind of short, which proved to be a frustrating combination for Freddie Prinze Jr. who reportedly hated working with Sutherland on 24 (2001-10) so much that he quit acting.

"Kiefer was the most unprofessional dude in the world," Prinze told ABC News. "That’s not me talking trash, I’d say it to his face, I think everyone that’s worked with him has said that."

After leaving 24, Prinze surprisingly went to work for wrestling promoter Vince McMahon, which he admitted was a different kind of crazy, but still preferable to working with Sutherland. "At least [McMahon] was cool and tall. I didn’t have to take my shoes off to do scenes with him, which [24] made me do. Just put the guy on an apple box or don’t hire me next time. You know I’m 6 feet and he’s 5’4."

In a statement to TMZ, Sutherland’s rep said this was the first the actor had heard about Prinze’s grievances, noting that Sutherland enjoyed the experience and wishes him the best. That isn’t exactly a denial, so we’re pretty sure these two aren’t going to play partners again anytime soon.

Bill Murray and Lucy Liu

When Charlie’s Angels: Full Throttle (2003) ramped up production, Bill Murray was noticeably absent from the sequel, despite playing series regular Bosley. According to The Playlist, the actor was allegedly brutal to Lucy Liu during the first film. He reportedly stopped a scene to insult her acting, which resulted in Liu throwing punches. After that, Murray refused to appear in the sequel if Liu was involved, and he found himself replaced by Bernie Mac, or so the story goes.

When asked about the incident almost a decade later by The Times of London (via Entertainment Weekly), Murray simply said, "Look, I will dismiss you completely if you are unprofessional and working with me… When our relationship is professional, and you’re not getting that done, forget it."

In the same interview, Murray also said that Charlie’s Angel director McG deserves to die by being "pierced by a lance," and Murray admitted to holding a grudge against Harold Ramis, one of his oldest friends and closest collaborators, for more than 20 years (said grudge ended because Ramis died.) In other words, don’t hold your breath for a Liu and Murray truce.

Shia LaBeouf and Alec Baldwin

In 2013, Shia LaBeouf and Alec Baldwin were set to appear in the Broadway production of Orphans until LaBeouf was fired from the show because of "creative differences," reportedly at Baldwin’s request.

In a lengthy interview with Vulture, Baldwin described his version of events: LaBeouf showed up to the set with a "jailhouse mentality" and began sending Baldwin videos where he recited entire scenes from memory. Eventually, the situation went nuclear when LaBeouf told Baldwin during rehearsal that he was "slowing him down." At that point, Baldwin asked to be removed from the show, but the director chose to fire LaBeouf instead.

A year later, LaBeouf told Interview that his method acting got the best of him. He also said that his goal was to "intimidate the f**k out of Baldwin," and he admitted that he started following Baldwin home after he got fired from the play. Needless to say, the situation got way out of hand.

According to LaBeouf, the two actors have since made amends, but we don’t suspect Baldwin will be inviting a lurking LaBeouf inside for a cup of coffee anytime soon.

Tom Hardy and Charlize Theron

Mad Max: Fury Road (2015) may have been a box-office success and a hit with critics, but behind-the-scenes, stars Charlize Theron and Tom Hardy did not get along. At all. In interviews, Theron wasn’t shy about confirming the rumors that she "struggled" with Hardy, and director George Miller even admitted that Theron and Hardy didn’t have the best relationship, according to People.

While sitting down with Esquire, Theron went even further by bluntly revealing that the two actors "f**kin’ went at it," which she blamed on Hardy’s personality and filming conditions that involved them constantly working on a moving truck in the desert. "It was like a family road trip that just never went anywhere," Theron said. "We never got anywhere. We just drove. We drove into nothingness, and that was maddening sometimes."

In 2017, co-star Zoe Kravitz confirmed the feud between Theron and Hardy, which she partially blamed on the grueling production. "They didn’t get along" Kravitz revealed on Watch What Happens Live! (via Cinemablend). "We were also in the desert for so long. I think everyone was tired, and confused, and homesick. We saw nothing but sand for six months. You go crazy, you do. I actually don’t know if there was one issue. I just think it was like they weren’t vibing."

Both Theron and Hardy are game for a Mad Max sequel, so buckle your seat belts, folks.