O'Mara was born Frances Meredith Carroll to John F. Carroll, an RAF flying instructor, and actress Hazel Bainbridge (born Edith Marion Bainbridge; 25 January 1910 - 7 January 1998). Her younger sister is actress Belinda Carroll. After boarding school she attended art school before becoming a full-time actress. O'Mara made her stage debut in a production of The Merchant of Venice in 1963, although her first film role was some years earlier (under the name Merrie Carroll) in Home and Away (1956) with Jack Warner, as her father, and Kathleen Harrison.  Her earliest television appearances, in the 1960s, included guest roles in Danger Man, Adam Adamant Lives!, The Saint, Z-Cars and The Avengers. In 1970, she appeared in two Hammer Studio horror films: The Vampire Lovers and The Horror of Frankenstein. In the former, she had an erotically charged scene with Ingrid Pitt, in which O'Mara was meant to be seduced; the two women were left laughing on set, however, as Pitt's fangs kept falling into O'Mara's cleavage. O'Mara's work in The Vampire Lovers impressed Hammer enough for them to offer her a contract, which she turned down, fearful of being typecast.  She had a regular role in the BBC drama series The Brothers (1975-76) as Jane Maxwell, and in the early 1980s, O'Mara starred in the BBC soap opera Triangle (1981-82), sometimes counted among the worst television series ever made. She played the villainous Rani in Doctor Who. The character, as played by O'Mara, appeared in two serials, The Mark of the Rani (1985) and Time and the Rani (1987) and the Doctor Who 30th Anniversary Special Dimensions in Time (1993), part of the Children in Need charity event.  Between these appearances in Doctor Who, she played Caress Morell in the American primetime soap opera Dynasty. As the sister of Alexis Colby (Joan Collins), O'Mara appeared in 17 episodes of the sixth season and 4 episodes of the seventh during 1986. "We had a tremendous bitchy tension between us", the actress recalled about performing opposite Collins. "My character Caress was like an annoying little mosquito who just kept coming back and biting her." O'Mara disliked living in California, preferring the change of seasons in Britain, and to her relief was released from her five-year contract after Collins told the producers that having two brunettes in the series was a bad idea. After returning to the UK, she was cast as another scheming villain, Laura Wilde, in the BBC soap Howards' Way (1989-90).

Answer this question "WHAT WAS HER FIRST MOVIE ROLE" by extracting the answer from the text above.
Home and Away (1956) with Jack Warner, as her father, and Kathleen Harrison.