A 1933 novel by Nathanael West about a newspaper advice columnist. The protagonist, though a man, starts writing an agony aunt column under the name of Miss Lonelyhearts; initially treating it as a joke. However, he is overwhelmed by the misery of his readers (Seventeen-and-Desperate, Sick-Of-It-All, Pregnant Again, Broad Shoulders, and the rest), who seem to all lead pathetic lives of despair and pain, and he comes to view himself as a Christ-like figure. Miss Lonelyhearts is a very funny tragedy about a vain and deluded man. Although a very short novel (around 60 pages in some editions), it manages to cram a great deal of detail in, in contrast to West's other, longer masterpiece The Day of the Locust, which is sometimes rambling and diffuse.

The novel presents a cold and clinical portrait of growing mental illness. West based it on a case history in William James's The Varieties of Religious Experience, and has explained that his goal in writing was to get away from the vague psychologising of nineteenth century literature, and replace them with the facts of psychological research. West illustrates the title character's instability through a number of means, including the recounting of strange dreams in which he finds himself arranging the symbols of consumerism into a variety of shapes including a phallus and a crucifix; this is intended to represent a search for meaning while trapped in shallow capitalism. Another prominent symbol is that of the deadpan or "dead Pan", a reference to the Greek god of wild drunken revelry and sexual abandon; West sees modern society as sexually and emotionally repressed.

In addition to its psychological realism, the novel, set in the early 1930s, presents a vivid world of cynical newspapermen and speak-easies. It is set mainly in New York (although the setting is never officially named), with a brief pastoral escape in Connecticut before it returns to the grimness of the city.

The main characters in addition to Miss Lonelyhearts are Betty, who is in love with him and sticks by him through his increasing madness; Willy Shrike, the ultra-cynical newspaper proprietor who mocks the hero's growing conscience; Fay Doyle, an overweight correspondent of Miss Lonelyhearts; and Peter Doyle, her crippled husband.

Miss Lonelyhearts was filmed twice, first as Advice to the Lovelorn in 1933, which starred Toby Prentiss and was directed by Alfred L. Werker. Nathanael West worked briefly on the screenplay for this film, although he did not contribute greatly, and the film is not highly rated. It was remade with more fidelity to the book in 1983 as Miss Lonelyhearts, starring Eric Roberts in the title role, Arthur Hill as Shrike, and Martina Deignan as Betty, and directed by Michael Dinner.