The Omega Man is a 1971 American science fiction film directed by Boris Sagal and starring Charlton Heston. It is based on the novel I Am Legend (1954) by American writer Richard Matheson. The screenplay is by John William and Joyce Corrington, and it was filmed in Technicolor with monaural sound, with a running time of 98 minutes. The story was first filmed as The Last Man on Earth (1964) featuring Vincent Price. A third adaptation of the novel, I Am Legend featuring Will Smith, was released in 2007, and an unofficial fourth, I Am Omega, featuring Mark Dacascos, was also released in 2007 (though neither Matheson's name or novel were credited as source material for this version).

As multiple reviewers have noted, the film differs from its source in several ways including the basic premise. In the novel the cause of the demise of humanity is a plague spread by mosquitoes, whereas in the film human biological warfare is the cause. One reviewer speculated this may have been due to one of the screenwriters having a doctorate in chemistry.