The Evil Dead is a series of media that originated from a trilogy of horror films created by Sam Raimi. The films focus on the protagonist, Ashley "Ash" J. Williams, who is played by Bruce Campbell. Ash deals with 'deadites', which are demons created by the Necronomicon.
Within the Woods
While it is not technically a part of the series, Within the Woods was the first creation in what would become the Evil Dead universe. It was made to secure funds to make The Evil Dead properly.
The Evil Dead
Released in 1981, this is the first official film in the series. It introduces the series' protagonist, Ash, and the Book of the Dead and what it brings with it. The Evil Dead is a horror movie with some elements of black comedy.
Evil Dead II
Released in 1987, this is the film that introduced the series' trademark humor, while expanding on the horror themes of Ash's dealings with the Necronomicon and demons.
Evil Dead III: Army of Darkness
Released in 1993, this is the last film in the trilogy, taking Ash back in time to England in 1300 AD. The movie has horror attributes, but is based mainly on humor and action. This time the evil creatures are referred to as deadites.
Army of Darkness has 2 alternative endings. This collection has both versions.