Oh it’s FIEND WITHOUT A FACE and its concept is absolutely unbeatable.
(Spoilers for an ancient b-movie?)
Radiation from an experimental power plant brings one man’s “evil thoughts” to life as an invisible something that sucks out his brain and spine, then stalks the countryside sucking out more brains, or so we think!!!
When the heroes find a way to render “the fiend” visible it turns out it was just the brain itself that got up and left, and every other missing brain is another “fiend” too!
They shoot the movie like there’s just one invisible monster roaming around and then it turns out it’s a whole fucking outbreak of people’s brains going rogue and turning new brains to their side, a brain revolt!
This movie is ten years older than “Night of the Living Dead” and therefore older than the entire concept of a zombie apocalypse but has many clear similarities, though it’s much more imaginative and I think the idea is a whole lot more horrifying.
It even culminates in the survivors boarding up an old house to fight off the brain horde!
Monsters and Stuff 