This study examines the presence of mental disorder in a number of famous novels. The retarded and mentally disturbed/disordered characters are "different", "less intelligent", idiotic, and they lack control over their mental activity. These novels provide clues as to how these individuals think and talk strangely in the eyes of ordinary and sane people. The novelistic products of the best-known authors, simply, are the fruit of observing the characters and the verbal expression of such characters in the context of the unfolding action involving the methods of story-telling. In this process, and in order to facilitate the narration, symbols, settings, chronological sequences, mannerisms, and distinctive features are used and required. This is basically because the mentally disturbed/disordered character is flat and unable to develop from experience. The roots of the mentally disordered or stupid characters go back to Shakespeare, who used the fool, the clown, the simpleton, and the simple-minded imbeciles for comic relief in his plays or for unexpected philosophical turns to throw light on questions that were pressing the heroic age of England in the years of formation of the English Identity. But, in fiction, which is from the post-Shakespearean age, the writer who paid much attention to the disordered mind of a mentally-retarded character was Laurence Sterne (1715-1768). It is he who made it possible for Faulkner and Mark Haddon to follow this style and keep on the trend.