Bo Derek (born Mary Cathleen Collins; November 20, 1956) is an American actress and model. She began her career as a child model before deciding to pursue acting on the advice of a talent agent she met through actress Ann-Margret, who was acquainted with her parents. In 1972, she was cast in the romantic drama film Once Upon a Love (1973), which was directed by her first husband John Derek and eventually released as Fantasies in 1981. Her breakthrough performance came in the romantic comedy film 10 (1979), which cemented her status as a sex icon and mainstream celebrity. The role earned her a Golden Globe Award nomination for New Star of the Year – Actress.

Derek went on to star in three more films directed by John Derek: Tarzan, the Ape Man (1981), Bolero (1984), and Ghosts Can't Do It (1989), all of which were critically panned. Her other credits include the dramatic-comedy film A Change of Seasons (1980), the American buddy comedy film Tommy Boy (1995), and the American telenovela series Fashion House (2006).

Derek has been involved in a number of philanthropic endeavors. For several years, she served as Honorary Chairperson for Veterans Affairs' National Rehabilitation Special Events, which helps disabled veterans overcome their limitations through sports and competition. In 2002, she was appointed to the Kennedy Center Board of Trustees by President George W. Bush. A longtime WildAid ambassador, Derek was named Special Envoy of the Secretary of State for Wildlife Tracking Issues by Deputy Secretary of State Robert Zoellick in 2006. In 2008, she was appointed a commissioner of the California Horse Racing Board by California Governor Arnold Schwarzenegger in honor of her many contributions to the betterment of horses, including her position as a spokesperson for the American Horse Slaughter Prevention Act, which she had held since 2003. She was reappointed to the California Horse Racing Board in 2010 and 2014.

Widowed in 1998, Derek began a relationship with actor John Corbett in 2002. They married in December 2020.

Derek was born Mary Cathleen Collins in Long Beach, California. Her father, Paul Collins, was a Hobie Cat executive, and her mother Norma (née White) was a make-up artist and hairdresser to Ann-Margret. Collins's parents divorced, and her mother married stunt performer Bobby Bass. She grew up with two sisters and a brother.

Collins attended Narbonne High School in Harbor City, California. She remarked in a 1985 interview on Late Night with David Letterman:

Well, I didn't really mean to quit. Well, what happened—I'll tell you what happened ... I went for like a month without going to school; I went to the beach, and I got caught ... So, then I started going back to school, and I was really enjoying it ... and then I went to go do this film with John in Greece ...

While attending Narbonne High School at age 16 in 1972, Collins auditioned for the female lead in John Derek's Once Upon a Love, a low-budget romantic drama film set in Greece. Although Derek had been considering Collins for the part, he felt that her naturally blonde hair was ill-suited to the character, whom he perceived as a brunette. He nevertheless offered Collins the role on condition that she dye her hair darker, which Collins accepted. During post-production in Munich, the film ran out of funding and was seized by a German film lab. It remained in a vault for several years until being sold to producer Kevin Casselman. Casselman's attempts to distribute the film globally prompted Derek and Collins to seek a restraining order against its release. They eventually dropped any legal action, deciding it was not worth their time and effort. The film was finally released in 1981 under the new title Fantasies, at which point it received negative reviews.