The appearance of mental illness in Middle-earth has been discussed by scholars of literature and by psychiatrists. Middle-earth is the fantasy world created by J. R. R. Tolkien. His novels The Hobbit and The Lord of the Rings are both set in Middle-earth and are peopled with realistically-drawn characters who experience life much as people do in the real world. Characters as diverse as Denethor, Théoden, Beorn, Gollum, and Frodo have been seen as possibly exemplifying conditions including paranoia, bipolar depression, schizoid personality disorder, post-traumatic stress disorder, and dissociative amnesia.
Tolkien's depiction of Frodo's mental suffering may derive from his own wartime experience. Scholars state that his friend C. S. Lewis was interested in Jungian psychology and the collective unconscious; Tolkien used these concepts in several places. Middle-earth is known to fans both through Tolkien's writings and through other media, notably Peter Jackson's The Lord of the Rings film series. In a celebrated scene, Jackson's 2002 film The Lord of the Rings: The Two Towers depicts Gollum/Sméagol talking to himself, using the device of shot/reverse shot to switch between the two personalities.
Tolkien fans have discussed Gollum's diagnosis on over 1300 websites. A supervised study by medical students, in a paper that uses both Tolkien's and Jackson's depictions of the character, concluded that Gollum does not meet the criteria for schizophrenia or multiple personality disorder, but that he meets 7 of 9 criteria for schizoid personality disorder. Some psychiatrists have suggested that The Lord of the Rings offers useful and "very tangible" lessons for mental health by helping readers to envisage and empathise with the situations of other people.