11The Thing (1982)
Shapeshifters show up on this list a few times, and it’s not hard to see why. Being completely unable to trust anyone (or anything) around you is bound to engender some terror, but even in that regard The Thing stands alone. Part of that is the incredible design from Rob Bottin (and a little help from special effects master Stan Winston), who brought the Thing to life in a viscerally, veiny fashion. Director John Carpenter takes a methodical approach to telling the story of a group of scientists trapped on an arctic base with a thing from another world. The location’s isolation is important—they have no one who can help except each other, but one of them isn’t what they appear to be.
While the paranoia might be terrible, the transformation scenes are even worse. The Thing’s forms strike the brain as something fundamentally wrong, from the spider head to the dog form it takes, everything about it seems to leap out at the viewer as dangerous, like a crime scene made of knives and teeth.