My Stepmother Is an Alien is a 1988 American science fiction comedy film directed by Richard Benjamin. It stars Dan Aykroyd, Kim Basinger, Jon Lovitz, and Alyson Hannigan. The film follows the story of Celeste, an extraterrestrial woman who is sent on a secret mission to Earth, after her home planet's gravity is mistakenly disrupted by Steven Mills, a widowed scientist raising his daughter Jessie as a single father. The film was the film debut of Juliette Lewis.

The screenplay was written by Herschel Weingrod, Timothy Harris, and Jonathan Reynolds, based on an earlier script by Jericho Stone. Stone had originally pitched the film to Paramount Pictures as a drama that would serve as an allegory for child abuse. When Paramount optioned the story, they suggested that it would be more believable as a comedy. The film was unproduced for four years until Weintraub Entertainment Group put it into production in 1988.

My Stepmother Is an Alien was a box-office bomb, grossing only $13.8 million against a $19 million budget. The film also received negative reviews from critics, with most of the responses panning the film's humor and screenplay. Basinger and costar Lovitz received generally favorable reviews for their comedic performances, but in a New York Times review, Aykroyd was singled out for criticism for his performance as a romantic lead.