5. In A Glass Cage (1987)
Backstory: A twisted Spanish psycho-horror which falls back on the go-to atrocity trope: Nazi war crimes. Here, a one-time concentration camp Doctor (one who abused boys in his 'care') is confined to an iron lung. His new nurse, Angelo, turns out to be one of his previous, deeply traumatised victims. But Angelo isn't just there for revenge, but to ultimately take his abuser's place, emulating his past actions with a new series of crimes of his own.
Sickest Scene: Holocaust survivor Angelo climbing on killer Klaus' iron lung and masturbating all over his trapped, blinking face.
4. Eraserhead (1977)
Backstory: David Lynch's first full-length movie, made totally independently over four years of snatched funding and free weekends. The finished film is remarkably consistent, and thoroughly dark - an intense dream world of rumbling sound and industrial landscapes that reflects the anxiety of new father Henry. There are stand-out moments of twisting horror, but the film's real, brilliantly unsettling power comes through the thick, indefinably troubling nature of its cold, oppressive atmosphere.
Sickest Scene: The climactic, cathartic moment when Henry cuts open his deformed baby's swaddling to find exposed organs underneath and, recoiling in horror, stabs the raw flesh.
3. Audition (1999)
Backstory: This second entry from one-man splat factory Takashi Miike is actually far subtler than his more extravagantly bloody work - although best known for his extreme film-making, Miike is a hell of an eclectic and accomplished director. A creeping horror of atmosphere and tension, with a middle-aged widower romancing a curiously deferential younger woman, Audition only erupts into cringe-inducing violence during its closing minutes.
Sickest Scene: The excruciating torture sequence during which long, thick needles are inserted into our paralysed hero's eyes. Or the one in which the protagonist's would-be fiance feeds puke to her captive gimp-dog man at home.
2. Threads (1984)
Backstory: A drab, documentary-style BBC film depicting in kitchen sink detail what would happen if Sheffield and the rest of the UK suffered a nuclear attack. The answer unsurprisingly, turns out to be mostly despair, chaos, and a painfully slow apocalypse.
Sickest Scene: The desolate closer. A disfigured baby is born in a reduced-to-medieval-standards society, where diseased survivors fight over diseased cattle. Living in the UK can frequently be disappointing, but Threads cranks it up to the next, bleakest level.
1. The Exorcist (1973)
Backstory: William Friedkin's notoriously, supernaturally shocking possession nasty, from William Peter Blatty's book. The film's powerfully raw aesthetic left audiences fainting, and religious conservatives convinced the celluloid itself contained a physical evil. It's the contrast between profound, uncaring cosmic horror and mundane, everyday aesthetic that does it. The atmosphere in that house is chokingly oppressive as a result.
Sickest Scene: Bedevilled child Regan MacNeil stabs her crotch with a metal crucifix and screams "Let Jesus fuck you!" in her inhuman voice. Aggressively unsettling now, and so, so much moreso in 1973.