The 1981 independent horror film directed by Sam Raimi that introduced Ash Williams is The Evil Dead.
The story follows five college students who visit an isolated cabin and discover an audio recording that awakens demonic forces. Bruce Campbell plays Ash Williams, initially an ordinary young man who becomes the lone survivor of the cabin’s supernatural attack and the central figure of the wider Evil Dead franchise.
Raimi and his collaborators developed the feature from Within the Woods, a 1978 short film made as a proof of concept for potential investors. The production was famously difficult, involving remote-location shooting, elaborate prosthetic effects, stop-motion work, and a very small budget. The completed film first screened privately in Detroit in October 1981 before gaining wider attention.
The most common confusion is with Evil Dead II, which also stars Ash and revisits elements of the original story. Army of Darkness is the later third film in Raimi’s original trilogy. The Evil Dead is the title that first introduced both Ash and the series’ demonic mythology.