When it comes to making a classic film, a good script goes a long way, but you may be surprised to learn that some of the best bits in your favorite scary flicks were actually unscripted horror movie moments. Ad-libs are common in comedy, but they're unexpectedly frequent in horror, too. Maybe that's because scares, like laughs, are often best elicited when they're unexpected. From horror comedies like Ghostbusters and Shaun of the Dead to some of the scariest found-footage horror movies like The Blair Witch Project, which was almost entirely unscripted, this list of improvised horror movie scenes shows that sometimes the scariest (and funniest) sequences are the ones that happen organically in the moment.
Some of these ad-libs were planned, as in Blair Witch, while others were spur-of-the-moment one-liners, inside jokes, or even gags that the actors were playing on the crew. Sometimes, the directors loved the new line so much they kept it in; other times, they had to be convinced. But always, it's hard to imagine these horror flicks without these famous improvised lines and scenes.