Jacqueline Susann's Once Is Not Enough is a 1975 American romance film, directed by Guy Green, starring Kirk Douglas, Alexis Smith, David Janssen, George Hamilton, Brenda Vaccaro, Melina Mercouri, and Deborah Raffin. It was produced by Howard W. Koch and written by Julius J. Epstein, based on the 1973 novel of the same name by Jacqueline Susann.

Margaret Alexis Smith was a Canadian-born American actress, pin-up girl and singer. She appeared in several major Hollywood films in the 1940s and had a notable career on Broadway in the 1970s, winning a Tony Award in 1972 for the Stephen Sondheim-James Goldman musical Follies.