Acting sure is a weird and wonderful profession, because as much as everyone involved knows they're simply playing pretend for the cameras, that doesn't mean authentic emotions aren't felt by performers as they get immersed in a scene.
Even though an actor will be well aware they're simply acting out an intense or scary sequence, that doesn't prevent at least some of that fear from transpiring through to them for one reason or another.
It's a testament to the committed work of their co-star, really, who proved so intimidating - whether in the horror genre or not - that they made their scene-mate lose their place and even straight-up forget their lines.
Maybe they deliberately tried to scare the hell out of their scene partner as the script required, or perhaps they simply cut such a statuesque presence on set that their lesser-known colleagues felt wildly inadequate by comparison.
Whatever the reason, these actors drove fear into the hearts of those who had to work opposite them, even if in many cases the movies were actually all the better for it...
8. Ben Kingsley Scared Several Cast Members - Sexy Beast
Jonathan Glazer's Sexy Beast is a terrific crime comedy best remembered for Ben Kingsley's superbly terrifying performance as sociopathic criminal Don Logan. It's a performance so brilliantly against-type, in fact, that it netted him a well-earned Best Supporting Actor Oscar nomination.
Since the film's release, it's been reported many times that several of Kingsley's co-stars were so taken aback by his unexpectedly fiery, aggressive, and intense performance that they'd occasionally forget their own dialogue.
And so, when you see Ray Winstone's Gal barely able to maintain eye contact with Don Logan throughout the movie, at least some of that unease might well be Winstone's own discomfort at how brilliantly fearsome Kingsley is.
While it won't always be productive on a film set to creep out your co-stars, in the case of Sexy Beast - a film hinged around Kingsley's character in many respects - it absolutely worked. Kingsley commands the screen every time he's on it, while holding his fellow actors firmly in his grip.