Deadites are creatures, most commonly people, that have become possessed by evil spirits (demons) in the Evil Dead universe. However, monsters and creatures released by The Necronomicon Ex-Mortis can be referred to as Deadites as well. Deadites that have chosen a human vassal appear as humanoid figures with glowing white eyes, charcoal-gray skin, and greatly elongonated teeth, often sharpened to fangs, while those that are monsters can appear as skulls with wings or goblin-like creatures, many of which have wings (Army of Darkness). They also have a variety of monsterous forms. In The Evil Dead, when people became possessed, their looks and physical characteristics worsened and took on a more decaying look the longer they were possessed, it can be assumed that when given enough time they transform into deformed beasts. In The Evil Dead, Professor Knowby warned via his tape recordings that he feared the only way to stop those possessed by the demons (Deadites) was throught the act of bodily dismemberment. Also in the same film, he warned that the book said that these enduring creatures may lie dormant but were never truly dead. However, at the ending of Evil Dead II, Ash killed a flying Deadite, resembling a goblin, by shooting its head with his "boomstick" (12 guage double-barrel Remington), meaning that it is possible to kill a Deadite but it takes a lot of effort.

When a human becomes a Deadite, it is assumable that they have no control over their physical body. What happens to their own soul or spirit remains unclear. In the films, no one who has ever become a deadite was ever released or returned to normal except in a few cases. These cases were when the demons wanted to trick Ash (Evil Dead 1) and others (Evil Dead 2) into letting them out of the fruit cellar of the cabin so they could wreak havoc. The only other cases were in Evil Dead 2 when a demon temporarily possessed Ash but was chased away by morning sunlight, after which Ash was returned to normal. Also when Ash was possessed he regained control of himself after seeing the necklace he'd given Linda earlier in the film and thus remembering her. And in Army of darkness when Sheila is turned back to normal when the battle of Humans and Deadites is finished