Marceline Day was an American motion picture actress whose career began as a child in the 1910s and ended in the 1930s.
Born Marceline Newlin in Colorado Springs, Colorado and raised in Salt Lake City, Utah, she was the younger sister of film actress Alice Day.
Day began her film career after her sister, Alice Day, became a featured actress as one of the Sennett Bathing Beauties in one and two-reel comedies for Keystone Studios. Day made her first film appearance alongside her sister in the 1924 Mack Sennett comedy Picking Peaches before being cast in a string of comedy shorts opposite actor Harry Langdon and a stint in early Hollywood Westerns opposite such silent film cowboy stars as Hoot Gibson, Art Acord and Jack Hoxie. Gradually, Day began appearing in more dramatic roles opposite such esteemed actors of the era as Lionel Barrymore, John Barrymore, Norman Kerry, Ramón Novarro, Buster Keaton, and Lon Chaney.
In 1926, Day was named one of the thirteen WAMPAS Baby Stars, a promotional campaign sponsored by the Western Association of Motion Picture Advertisers in the United States, which honored thirteen young women each year who they believed to be on the threshold of movie stardom. Other notable recipients that year were Joan Crawford, Mary Astor, Janet Gaynor and Dolores del Río. The publicity from the campaign added to Day's popularity and in 1927 she appeared opposite John Barrymore in the romantic adventure The Beloved Rogue.