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 exemplifying conditions including paranoia, bipolar depression, schizoid personality disorder, and post-traumatic stress disorder.
Tolkien's depiction of Frodo's mental suffering may derive from his own wartime experience. His friend C. S. Lewis was interested in Jungian psychology and the collective unconscious and probably shared these ideas with Tolkien; Tolkien used the concepts in several places.
Tolkien fans have discussed Gollum's diagnosis on over 1300 websites. A supervised study by medical students concluded that Gollum met many of the criteria for schizoid personality disorder. In a celebrated scene, Peter 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.