NBC, and Gunsmoke, Have Gun – Will Travel, and Rawhide on CBS. In 1958, Lockhart was the narrator for Playhouse 90s telecast of the George Balanchine version of Tchaikovsky's The Nutcracker, featuring Balanchine himself as Drosselmeyer, along with the New York City Ballet. Lockhart is best known for her roles as TV mothers, first as Ruth Martin, the wife of Paul Martin (portrayed by Hugh Reilly) and the mother of Timmy Martin (played by Jon Provost) in the 1950s CBS series Lassie (a role that she played from 1958 to 1964). She replaced actress Cloris Leachman, who, in turn, had replaced Jan Clayton – who had played a similar character earlier in the series. Following her five-year run on Lassie, Lockhart made a guest appearance on Perry Mason as defendant Mona Stanton Harvey in "The Case of the Scandalous Sculptor". Lockhart then starred as Dr. Maureen Robinson in Lost in Space, which ran from 1965 to 1968 on CBS, opposite veteran actors Guy Williams and Jonathan Harris. In 1965, Lockhart played librarian Ina Coolbrith, first poet laureate of California, in the episode "Magic Locket" of the syndicated Western series, Death Valley Days. Lockhart then appeared as Dr. Janet Craig on the final two seasons of the CBS sitcom Petticoat Junction (1968–1970); her character was brought in to fill the void created after Bea Benaderet died during the run of the show. She was a regular in the ABC soap opera General Hospital during the 1980s and 1990s, and was also a voice actor, providing the voice of Martha Day, the lead character in the Hanna-Barbera animated series These Are the Days on ABC during the 1970s. Lockhart appeared as a hostess on the Miss USA Pageant on CBS for six years, the Miss Universe Pageant on CBS for six years, the Tournament of Roses Parade on CBS for eight years, and the Thanksgiving Parade on CBS for five years. In 1986, Lockhart appeared in the fantasy film, Troll. The younger version of her character in that film was played by her daughter, Anne Lockhart. They had previously played the same woman at two different ages in the "Lest We Forget" episode of the television series Magnum, P.I. (1981). In 1991, Lockhart appeared as Miss Wiltrout, Michelle Tanner's kindergarten teacher on the TV sitcom Full House. She also had a cameo in the 1998 film Lost in Space, based on the