Born as Lois Mae Green in Deer Lodge, Montana, she appeared in 70 movies from 1932 through 1966. She was discovered by Ida Koverman, secretary to MGM mogul Louis B. Mayer, after she saw a poster featuring Parker portraying Father Time. She attended Pasadena schools and graduated from John Muir High School. Her original aspirations were in the fine arts and illustration.

She had a successful career at MGM, RKO and Columbia including important roles such as the tragic Beth in the original Little Women, among many other film appearances including Frank Capra's Lady for a Day and Gabriel Over the White House; Sequoia; The Ghost Goes West, opposite Robert Donat; and Rasputin and the Empress, with fellow players, the Barrymore siblings (John, Ethel, and Lionel) in the only movie they all made together. In 1939, she starred opposite Stan Laurel and Oliver Hardy in RKO's The Flying Deuces.

Parker stayed active in film throughout the 1940s, playing opposite Lon Chaney in Dead Man's Eyes, and a variety of other films. Parker managed her own airport and flying service with then-husband Doug Dawson in Palm Springs, California until shortly after the start of World War II. During the war, she toured many of the veteran hospitals throughout the U.S. and performed on radio. In the 1950s, Parker co-starred opposite Edward G. Robinson in Black Tuesday; had a small but effective role in The Gunfighter which starred Gregory Peck and appeared with Randolph Scott and Angela Lansbury in the western Lawless Street (1955). Her last film appearance was Apache Uprising (1966), directed by A. C. Lyles.

Parker also appeared on Broadway. In 1949, she replaced Judy Holliday in Born Yesterday on Broadway and enjoyed a successful run in this classic. Parker also appeared on Broadway opposite Bert Lahr in the play Burlesque, did summer stock in Bucks County, Pennsylvania, was on tour in the play Candlelight and Loco, and performed on stage in other professional productions.

In 1950, she married Robert Lowery, who had played Batman in 1949. In 1952, Parker gave birth to a son, Robert Lowery Hanks, later an executive with the city of Los Angeles. In 1954, Parker played the role of Cattle Kate Watson of Wyoming in an episode of the syndicated television series Stories of the Century, the first western program to win an Emmy Award. The series starred and was narrated by Jim Davis.^[1]

Later in life, Parker continued a successful stint on the West Coast theatre circuit and worked as an acting coach.

She spent her final years in the Motion Picture and Television Country House and Hospital in Woodland Hills, California, where she died of a stroke on November 30, 2005, at the age of ninety.