Fans and critics alike often ask actors whether acting in a scary movie is as terrifying an experience as watching it, and generally the answer tends to be "no," that the artifice of a film set strips away most of the fear that's ultimately created in the edit bay.
But that doesn't mean actors always feel entirely in control of the situation they're in, or more to the point, that they're always able to control their emotions on command.
And so, actors have occasionally admitted to putting themselves in a position where, for one reason or another, they've genuinely scared themselves.
Perhaps they had trouble "switching off" from a troubling character after a shoot, maybe the disturbing material invaded their dreams, or even the shooting conditions they willingly put themselves through created tremendous anxiety.
Whatever the reason, these 10 actors all gave themselves The Fear in a major way, and while in some instances they went on to win major awards, even Oscars, for their work, they were clearly never the same afterwards.
With this knowledge in mind, you'll never be able to watch these performances quite the same way again...
10. Natalie Portman Worried She Was "Going To Die" - Black Swan
Darren Aronofsky is one of the most uncompromising filmmakers working today, and actors who sign up to star in his movies are clearly encouraged to entrench themselves as deeply as possible in their characters - see: Mickey Rourke in The Wrestler and Jennifer Lawrence in Mother!
And then there's Aronofsky's Black Swan, which scooped Natalie Portman a Best Actress Oscar for her performance as Nina Sayers, a ballet dancer whose grasp of reality begins to slip amid fierce competition.
But between the dark subject matter and intense training regimen Portman underwent for the role - including losing 20 pounds and working out up to eight hours per day - she ended up becoming fearful for her own life. She said:
"There were some nights that I thought I literally was going to die... It was the first time I understood how you could get so wrapped up in a role that it could sort of take you down."
Portman later followed up by admitting that she "probably should have gone into rehab" following the completion of filming, though instead threw herself headlong into shooting the first Thor film.
Portman's career and credibility certainly benefitted enormously from her committed to the role, even if she got a first-hand glimpse at how terrifying such extreme commitment can be.