Montgomery was the child of Hollywood royalty. Her father was Robert Montgomery, a top leading men of the 1930s and 40s who later became primarily a director and producer. She made her acting debut on her father's TV series, "Robert Montgomery Presents", in 1951. Not wanting to live in her father's shadow, Montgomery went back to New York to study at the American Academy of Dramatic Arts, but left to star in the National Theatre's production of "Late Love."
Armed with critical praise for her stage work, Montgomery again made an assault on Hollywood, with sporadic results. She appeared in many TV episodes and in such feature films as "The Court-Martial of Billy Mitchell" (1955) and Asher's "Johnny Cool" (1963), but to many she was merely the ingenue who married actor Gig Young, a dozen years her senior, in 1957, and whose quarrels were fodder for gossip column items. In 1961, she earned the first of her nine Emmy nominations portraying a gun moll in an episode of "The Untouchables" (ABC). Though she was one of the principals in "Who's Been Sleeping in My Bed?" a 1964 comedy feature, stardom proved elusive.
Having married Asher, Montgomery decided to concentrate on raising a family, but Asher suggested she do a TV series, where the hours could be conducive to being both a mother and an actor. In fact, after ABC bought "Bewitched", Montgomery gave birth to her first son and the crew shot around her for the first episodes of the series -- her work was edited in later. Cast alongside Dick York as her mortal husband, Agnes Moorehead as her meddling witch mother, and Marion Lorne as a befuddled witch aunt, "Bewtiched" carried Montgomery to fame. She even took on the occasional added role of Serena, Samantha's identical, but brunette, cousin. "Bewitched" survived a cast change in the role of Darren--Dick Sargent took over the part in 1969--and the death of several cast members to stay on ABC's schedule until 1972. After the demise of the series, and now divorced from Asher, Montgomery was offered series projects, but chose instead to become one of the first queens of TV-movies. Beginning in 1972, she would star in one and often two or more TV-movies or miniseries each season in roles ranging from a rape victim victimized in turn by society ("A Case of Rape," 1974) to Lizzie Borden in an acclaimed TV rendition of the story in 1975 to a pioneer in "The Awakening Land" (1978) to "Deadline for Murder", which aired on CBS just weeks before she died. The latter was the second film she did based on the work of real-life crime reporter Edna Buchanan.
Although rarely in the spotlight--an exception being her 1993 marriage to actor Robert Foxworth, her companion for 20 years, Montgomery did lend her name, support and often made substantial donations to a variety of progressive political and social causes. Critical of Reagan-Bush policies in Central America, she narrated the 1988 documentary "Cover-Up: Behind the Iran Contra Affair" and, in 1993, "The Panama Deception," which won an Academy Award. Montgomery was also one of the first celebrities who actively lent their name and likeness to AIDS causes, including AIDS Project Los Angeles. When Dick Sargent, her former TV husband, openly revealed his homosexuality in 1991, she was quick to publicly support him, and served as grand marshall with Sargent of the 1992 Gay Pride parade in West Hollywood. As always, Montgomery was quiet about her own private life--she had not given an interview in two decades--and when she succumbed to cancer in 1995, it took many in the TV community by surprise. "Bewitched" had been picked up by the cable channel Nickelodeon when Montgomery died, and its subsequent airings were bittersweet for fans for whom Samantha Stevens' twitching nose was nostalgia, and an unexpected pleasure for those for whom it was a discovery.