Marlo Thomas (born Margaret Julia Thomas on November 21, 1937 in Detroit, Michigan) is an American actress, who first achieved fame on the TV series That Girl in the 1960s.

She is the daughter of the late Lebanese-American comedian Danny Thomas and sister of Tony Thomas, a TV and film producer, and Terre Thomas, a former actress. Her mother, Rose Marie Mantell, was the adopted daughter of Italian Americans and died in 2000.

Thomas was born in Detroit, but grew up in Beverly Hills, California, and went by the nickname of Margie Thomas while attending school. She attended Marymount High School in Los Angeles. She graduated from the University of Southern California with a teaching degree and was a member of the sorority Kappa Alpha Theta. Afterward, she appeared as a regular on The Joey Bishop Show (1961 – 1962).

She followed the series with guest shots on Ben Casey, My Favorite Martian, and Bonanza, but it was not until 1966 that she hit her professional stride as aspiring New York actress Ann Marie on the ABC sitcom That Girl. The series ran until 1971, garnering her a Golden Globe Award and four Emmy nominations.

Anxious to show she was as adept at drama as she was at comedy, she proved herself in the television movies It Happened One Christmas (1977) (a remake of It's a Wonderful Life, with Thomas in the rewritten James Stewart role), Nobody's Child (1986) , and The Lost Honor Of Kathryn Beck (1984), while she starred in Jenny (1970) and Thieves (1977) on the big screen.

Thomas's Broadway theatre credits include Thieves (1974), Social Security (1986), and The Shadow Box (1994).

She is also known for her children's books and the recordings and television specials created in conjunction with them: Free to Be… You and Me (1972 and 1974) and Free to Be… A Family (1987), with Christopher Cerf, which were born out of an attempt to teach her then-young niece Dionne about life. She is donating all royalties from her 2004 book and CD, Thanks & Giving: All Year Long (also produced with Cerf), to the St. Jude Children's Research Hospital in Memphis, Tennessee. Started by her late father, the organization helps young children suffering from grave forms of disease, especially cancer and leukemia, including many whose parents do not have much money or health insurance; the services are free to all patients, although insurance is accepted from those who are insured.

Thomas has continued her legacy of charity and donation through her publications of The Right Words at the Right Time (6 January 2004, Atria Books ISBN 0-7434-4650-X) and The Right Words at the Right Time Volume 2 (25 April 2006, Atria Books ISBN 0-7434-9743-0). Both books are collections of essays written by celebrities and fans of Thomas, explaining when a friend, family member or perfect stranger said the right thing in the author's time of need. All proceeds go to her charity (St. Jude's Hospital).

Thomas's favorable public image came under severe attack in 1990 when her former butler Desmond Atholl wrote a book called That Girl and Phil (ISBN 978-0312051693). This was an expose of sorts of the years he worked for her. Atholl claimed that contrary to her public image, Marlo Thomas was cruel and foul mouthed towards her staffers, and servants.

In recent years, Thomas has appeared in guest shots on Ally McBeal, Friends (as Rachel's mother), and made several guest appearances on Law & Order: Special Victims Unit, playing attorney and former judge, Mary Conway Clark, who had a mentoring relationship with assistant District Attorney, Casey Novak. She also appeared in the 2000 comedy Playing Mona Lisa with Alicia Witt and Harvey Fierstein.

Thomas is the recipient of four Emmy Awards. She has been married to talk show host Phil Donahue since 1980. She has no children, but is stepmother to Donahue's five children from his previous marriage. The couple lives in New York City, but Thomas travels to Los Angeles for work or to receive donations to her charity, Saint Jude Children's Research Hospital. (Producer David Geffen contributed $1,000,000 by simply writing Thomas a cheque when she was on location in L.A. filming Friends some years ago.)

Many well-known and highly identifiable actresses have tried and failed to make the arduous crossover from fizzy TV sitcom star to mature, dramatic artist. Usually, it was their hardcore fans who refused to accept them in any other light. Sally Field and Elizabeth Montgomery (I) come to mind first as two actresses who somehow managed to make the none-too-easy adjustment. Marlo Thomas became another success story as well--but, like the others, it was none too easy. Adorable to a fault, Marlo seemed to have nowhere to go after the early 1970s when the cute and wholesome Ann Marie of "That Girl" (1966) was suddenly no more. Born in Deerfield, Michigan, on November 21, 1937, to parents of Lebanese origin, Marlo was christened Margaret Julia Thomas. She was raised in the mad whirl of the entertainment business as the daughter of show business legend Danny Thomas (I), who was very determined that she not become an actress, at least until after college graduation. She actually began her adult life as a schoolteacher, but it was a very half-hearted career choice. Marlo began with early TV appearances in the late 1950s on such series as "Many Loves of Dobie Gillis, The" (1959), "Zane Grey Theater" (1956) and "Thriller" (1960) Her first major break came when she was cast as Joey Bishop (I)'s sister and aspiring actress on the 1961 sitcom "Joey Bishop Show, The" (1961) for one season. She continued to build up her resume with assorted guest shots on "Bonanza" (1959), "McHale's Navy" (1962), "Donna Reed Show, The" (1958) and "Ben Casey" (1961). Following her delightful work on the London stage with "Barefoot in the Park" in 1965, she was finally given the opportunity to test for her own sitcom and passed with flying colors. Audiences adored the romantic entanglements and struggling ambition of "Ann Marie", a single, independent and very trendy young woman trying to make it as an actress in New York City. Marlo became an instant household name (as did co-star Ted Bessell) and nabbed a Golden Globe and four Emmy nominations during the show's five-year run. Following its demise in 1971, however, Marlo was faced with a problem: being stereotyped as a perky, wide-eyed innocent. Capitalizing on her TV fame, she tried to shatter her lightweight image with a serious film part. Playing the title role of Jenny (1970) opposite Alan Alda, Marlo starred as an unwed pregnant girl who marries a filmmaker out of convenience. Although the valiant effort brought her a Golden Globe nomination for Most Promising Newcomer, audiences stayed away in droves, much preferring her to be chipper and upbeat. She made her Broadway debut in the Herb Gardner play "Thieves" in 1974, and later made another stab at films by recreating her role for the big screen. The reviews for Thieves (1977) were less than ecstatic and no other strong offers came her way. Marlo decided to lay low for a time and wound up combining her deep love for children and education with her own career. She won bookend Emmy Awards as both star and producer of the children's specials Free to Be... You & Me (1974) (TV) in 1974 and Free to Be... a Family (1988) (TV). The album of the former continues to be in-print to the present day. By the late 1970s, however, audiences finally had stopped seeing her as only "Ann Marie". She earned renewed respect by stretching herself in TV movies. In the ABC holiday mini-movie It Happened One Christmas (1977) (TV), she played a troubled female version of James Stewart (I)'s It's a Wonderful Life (1946) character. She also won critical acclaim in the social, made-for-TV dramas Lost Honor of Kathryn Beck, The (1984) (TV) and Consenting Adult (1985) (TV). She also copped an additional Emmy trophy as Best Actress in a Special for Nobody's Child (1986) (TV). Her subsequent return visits to Broadway with "Social Security" (1986) and "The Shadow Box" (1994) were rewarding as well. She has certainly not shied away from demanding theater roles, such as "Beatrice" in "The Effect of Gamma Rays on Man-in-the-Moon Marigolds" (1990), "Martha" in "Who's Afraid of Virginia Woolf?" (1992) and Ouisa in "Six Degrees of Separation" (1992). Although Marlo wed rather late in life, her enduring show business marriage since 1980 to talk-show icon Phil Donahue (I) clearly indicates that the waiting was worthwhile. Still quite active on TV, she has continued to be a joy in everything from classic comedy (such as playing Jennifer Aniston's mom in "Friends" (1994)) to adult drama (as a lawyer/mentor in the highly-rated crime drama "Law & Order" (1990)). Younger brother Tony Thomas (I) and sister Terre Thomas have also had leanings toward show business. Tony has been a prolific TV and film producer over the years, and Terre has dabbled as an actress, once having a guest role on Marlo's sitcom, "That Girl" (1966). On a more personal level, Marlo has continued the tradition of her late father as both spokesperson and humanitarian for St. Jude's Children's Hospital for cancer research.