Things That Shouldn't Be There
Supernatural horror is built around a single premise: something exists that the rules of the world say cannot. A person who died is present. A shape appears that has no body to cast it. Something responds to your presence that has no sensory apparatus to detect you with.
The short film form handles this better than features in one specific way. Features have to explain. Not everything, not completely, but a feature-length supernatural horror film usually arrives at some account of what the entity is, where it came from, what it wants. Short films don't have to do this. They can leave the entity fully unexplained, present only in its effects, and the viewer accepts that. The brevity creates permission to withhold.
The best supernatural horror shorts use that permission completely.
Presence Without Explanation
The most effective supernatural horror shorts show you something is present without ever accounting for it. No backstory. No mythology. No character who explains what's happening to another character who stands in for the audience. Just presence, and the response to presence.
Think about why this works. Explanations domesticate the inexplicable. The moment you know where the ghost came from and why it's angry and what it wants, it becomes a problem to be solved rather than a thing to be feared. Short films sidestep this entirely. The entity exists. That's it. What do you do with that?
7 Supernatural Horror Shorts That Earn Their Dread
Lights Out (2013) is the obvious starting point. David F. Sandberg's original short works because it never explains the figure in the dark. She's there, she's dependent on darkness, and the film is about the pragmatic horror of having to live with that. Two and a half minutes and it's still the cleanest example of what this subgenre can do.
Mama (2008, dir. Andy Muschietti) is three minutes of two little girls being visited by their dead mother, a fast grotesque thing that moves wrong. Guillermo del Toro saw it and produced the feature. The creature design in this short is more effective than almost anything in the feature it spawned.
Ghost Train (2013, dir. Lee Cronin, who later directed Evil Dead Rise) follows two estranged brothers who revisit the fairground where their childhood friend vanished into a ghost train. The dread comes from what the train still contains. Won the Melies d'Argent for Best European Fantastic Short Film.
Salt (2017, dir. Rob Savage, who later directed Host) is two minutes: a mother and sick daughter protected only by a ring of salt from a demonic presence. The economy is total. Nothing in those two minutes is wasted. Won Best Horror Short at Hollyshorts Film Festival.
The Birch (2016, dir. Ben Franklin and Anthony Melton) is about a bullied boy who uses a family spell book to summon an ancient being from the forest. The being that answers is not sympathetic, and neither is the boy by the end. Won a Webby Award in 2017 and spawned a Facebook Watch series.
The Facts in the Case of Mister Hollow (2008, dir. Rodrigo Gudino and Vincent Marcone) is an animated short that reveals its horror through close examination of a photograph. An occult ritual hidden across every detail of a single image, visible only if you look long enough. Won Best Short at Puchon International Fantastic Film Festival.
Red Balloon (2010, dir. Damien Mace and Alexis Wajsbrot) has a babysitter discover that a creepy doll in the girl's room doesn't actually exist in any photograph or memory. Something else is in the house. The misdirection is clean and the reveal lands hard.
Where to Find More
Supernatural horror shorts are the most common subgenre in short horror, which means both that there's more of it and that more of it is mediocre. Festival circuits, ALTER on YouTube, and FinTV's curated library are the most reliable sources for work that actually earns its scares rather than relying on jump cuts and loud sounds.
The best supernatural horror shorts leave a residue. You watch them and something shifts slightly. Later, in a dark room, you're aware of the corners. That's what this subgenre is for. The short form delivers it faster and sometimes more effectively than anything twice the length.