The Lonely Guy is a 1984 Steve Martin romantic comedy film, written by Neil Simon and directed by Arthur Hiller.

Based on the book "The Lonely Guy's Book of Life" by Bruce Jay Friedman, Martin portrays Larry Hubbard, a greeting card writer who goes through a period of terrible luck with women. At the pit of his despair, Hubbard writes a book titled A Guide for the Lonely Guy, which is rampantly successful and catapults him into an entirely different experience of life.

The film also stars Charles Grodin, Judith Ivey and Steve Lawrence and features cameo appearances from Merv Griffin, Dr. Joyce Brothers, and Loni Anderson. The theme song, "Love Comes Without Warning", was performed by America.