What is acting if not pretending, of assuming a mood or personality different to that which comes naturally?
This usually requires actors to "get in the zone," but sometimes it'll simply mean trying to suppress the fact they just can't stand the person they're working with.
Of course, it's no requirement that actors need to get along in order to work together or even make a great movie, but most of the time some professional cordiality definitely helps.
These 10 actorly pairings, however, afforded one another no such quarter, opting instead to square up and go toe-to-toe throughout shooting.
Whether the result of their own planet-sized egos or the simply problematic, difficult nature of the production, these films evidently brought out the worst in their stars.
In some cases it sadly undermined what we saw on screen, while in some fortunate examples it only helped feed the tension and anxiety that the film desperately needed.
While the experience caused some actors to swear off working with their co-star ever again, in others the juice proved very much worth the tricky squeeze...
10. Tom Hardy & Charlize Theron - Mad Max: Fury Road
As masterful as Mad Max: Fury Road turned out, it was against the considerable adversity of not only a physically gruelling production for all involved, but also the intense conflict between stars Tom Hardy and Charlize Theron.
Rather than support one another through the tricky shoot, Hardy and Theron became combative, both later mentioning how difficult they found it to see George Miller's vision for the film during production. Hardy said:
"I was in over my head in many ways. The pressure on both of us was overwhelming at times. What [Theron] 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."
Conversely, Theron added:
"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! 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.' In a weird way, we were functioning like our characters: everything was about survival."
Though the two clearly buried the hatchet once shooting wrapped and Fury Road went on to become one of the most acclaimed action films of all time, their inability to appreciate one another's difficult jobs resulted in months of resentment.