Thomas was born in Greenwich, Connecticut, to Gladdy Lou Ryder, a special education teacher in the Santa Monica-Malibu Unified School District. She graduated from Santa Monica High School in 1975 and went on to attend UCLA School of Theater, Film and Television, graduating in 1980. While at UCLA, she was a member of the Chi Omega sorority.
Thomas started acting at age 14, when she was one of the hosts of a series on NBC called Talking with a Giant, where she interviewed celebrities. In 1978 she began acting in small television roles; she appeared in the series Co-Ed Fever, of which she later said, “It was canceled after the third commercial.”
After Co-Ed Fever’s cancellation, Thomas was chosen for the role of Jody Banks in The Fall Guy, which starred Lee Majors and was produced by Glen Larson, from its 1981 premiere to its 1986 cancellation. Unfortunately, Thomas developed a cocaine addiction during her run in the program, and entered rehabilitation for that addiction in 1984. She appeared in several movies, the first of which was Zapped! in 1982 (see below for her filmography), but she gave up acting in 1998. Thomas appeared on numerous pin-up posters during the 1980s.
Following her acting career, Thomas wrote a screenplay called School Slut and sold it to Touchstone Pictures for a figure reported as “mid-six-figure.” Touchstone did not make the film, however, and Thomas acquired the rights to produce it herself.
In April 2008, Thomas’s first novel, Trophies, was published by William Morrow. Harrison Ford described it as having “made me laugh out loud… ironic, smart and surprisingly touching.” Arianna Huffington described the characters in Trophies as “…powerful women flawlessly draped in Vera Wang, [with] manicured hands pushing buttons while scratching their way to the top–the secret power brokers of Los Angeles. Heather Thomas has written a stiletto heel-sharp satiric romp.” 
Thomas married Allan Rosenthal in August 1985, Rosenthal is one of the founders of Cocaine Anonymous; they divorced in September 1986. Thomas then married entertainment attorney Skip Brittenham in October 1992. Their daughter, whom they named India Rose, was born on June 19, 2000. Thomas and Brittenham became joint hosts of a monthly fund-raising breakfast gathering at their home in Santa Monica, California, which became known in Washington as the “L.A. Cafe.” Thomas serves on the advisory boards of The Rape Foundation and Amazon Conservation Team. According to newsmeat.com, Thomas contributed over US$280,000 to political candidates since 1992, mostly to Democratic and special-interest groups, such as Sen. Barbara Boxer (D-CA), Sen. Elizabeth Warren (D-MA), and Sen. Al Franken (D-MN), with $2,400 towards supporting Republican Mary Bono.
|Kiss of the Cobra||Merryl Davis||Alternative titles: Death Stone
Der Stein des Todes
|1990||Red Blooded American Girl||Paula Bukowsky|
|1993||Hidden Obsession||Ellen Carlyle|
|1997||Against the Law||Felicity|
|2014||Girltrash: All Night Long||Nadine Robson|
|1978||David Cassidy: Man Undercover||Caryl Manning||1 episode|
|1979||Co-Ed Fever||Sandi||1 episode|
|California Fever||Joanne||1 episode|
|1980||B. J. and the Bear||Caroline Capote||1 episode|
|The Misadventures of Sheriff Lobo||Caroline Capote||1 episode|
|1981–1986||The Fall Guy||Jody Banks||111 episodes|
|1983||The Love Boat||Sheila||2 episodes|
|1984||T. J. Hooker||Sandy||1 episode|
|Cover Up||Amber||1 episode|
|1987||The New Mike Hammer||Andrea||1 episode|
|Ford: The Man and the Machine||Evangeline Cote||Television movie
Nominated: Gemini Award for Best Performance by a Supporting Actress
|Hoover vs. The Kennedys: The Second Civil War||Marilyn Monroe||Television movie|
|1988||The Dirty Dozen: The Fatal Mission||Lt. Carol Campbell||Television movie|
|1989||Rodney Dangerfield: Opening Night at Rodney’s Place||Joan Emery||Television movie|
|1991||P.S. I Luv U||Mary Markham||1 episode|
|1992||Swamp Thing: The Series||Tatania||1 episode|
|1995||Pointman||Lynn Forbes||1 episode|