The first horror movie ever made was The Haunted Castle in 1896, also titled Le Manoir du Diablo or Manor of the Devil. George Méliès was a French special effects coordinator that stumbled upon a technique that would inspire the first Horror Movie.
In the Autumn of 1896, an event occurred which has since passed into film folklore and changed the way Méliès looked at filmmaking. Whilst filming a simple street scene, Méliès camera jammed and it took him a few seconds to rectify the problem. Thinking no more about the incident, Méliès processed the film and was struck by the effect such a incident had on the scene – objects suddenly appeared, disappeared or were transformed into other objects. – earlycinema.com
Melies used what he accidentally learned to create the first horror movie and likely the first use of special effects to scare it’s audience in The Haunted Castle. Watch Free Below:

Artist Writes and Records in Haunted Houses
Halloween Coffee Mug
First Horror Movie
First Horror Film, First Horror Movie.