The overwhelming majority of horror films are reliant on effects in one way or another, whether classic practical, in-camera "SFX" or more contemporary image manipulation, aka "VFX."
Effects can make or break a horror movie, either elevating the tension established by the acting, direction, and atmosphere, or if the effects aren't up to scratch, derailing it entirely.
But what about those bad horror movies which lucked out with unexpectedly superb effects, effects which ensured the film wouldn't ever be forgotten?
These 10 horror films, each of them ill-received by critics and audiences alike, nevertheless live on thanks to the utterly impeccable, terrifying, and disgusting effects work that went on behind-the-scenes.
From nauseatingly creative gore effects to gnarly transformations, some impressively optical tricks, and everything in-between, these films were if nothing else a testament to the insane level of craft that can go into making even the worst movie.
Whatever you think of these films in terms of writing, direction, and acting, those responsible for the effects absolutely did their jobs.
But before you click onwards, it goes without saying that most of these entries are decidedly horrifying, if not totally NSFW. You've been warned...
10. The Lawyer Has To Split - Thirteen Ghosts
This remake of William Castle's 1960 haunted house film 13 Ghosts is perhaps the textbook example of a guilty pleasure - horribly written, poorly acted, choppily edited, and yet, alluringly trashy fun.
A big part of the appeal is the sublime work that went into the movie's practical production elements, pertaining to not only its impressive set design but also its revolting bursts of gore.
And if Thirteen Ghosts is remembered for any single scene, it's surely the glorious sequence where lawyer Ben Moss (J.R. Bourne) accidentally releases the titular ghosts from imprisonment, triggering a sliding door mechanism which immediately bisects him.
The stunning, mostly practical gore effects show Moss falling to the ground in two parts on either side of the doors, giving audiences a practically medical glimpse at his surgically sliced insides.
Director Steve Beck, who spent several years working at Industrial Light and Magic on films such as Indiana Jones and the Last Crusade and The Abyss, demonstrates a real aptitude for melding eye-popping practical and digital effects into a seamless whole.