Once Upon a Honeymoon is a 1942 romantic comedy/drama starring Cary Grant, Ginger Rogers, and Walter Slezak, directed by Leo McCarey, and released by RKO Radio Pictures. It was nominated for the Oscar for Best Sound Recording.

Walter Slezak was an Austrian-born film and stage actor active between 1922 and 1976. He mainly appeared in German films before migrating to the United States in 1930 and performing in numerous Hollywood productions.