Margaret Julia “Marlo” Thomas (born November 21, 1937) is an American actress, producer, and social activist known for her starring role on the TV series That Girl (1966–1971). She also serves as National Outreach Director for St. Jude Children's Research Hospital.
Thomas was born in Detroit, Michigan, the eldest child of Lebanese-American comedian Danny Thomas (1912–1991) and his wife, the former Rose Marie Cassaniti (1914–2000). On her mother's side, she is also the granddaughter of drummer and percussionist, Marie "Mary" Cassaniti (1896-1972). Her brother, Tony Thomas, is a television and film producer, and her sister, Terre Thomas, is a former actress.
Marlo Thomas was raised in Beverly Hills, California. Her parents called her Margo as a child, though she soon became known as Marlo, she told The New York Times, because of her childhood mispronunciation of the nickname. She attended Marymount High School in Los Angeles. Thomas graduated from the University of Southern California with a teaching degree; "I wanted a piece of paper that said I was qualified to do something," she said. She was also a member of the sorority Kappa Alpha Theta.