Born August 9, 1934, in New York, she said in a 2016 interview that she first studied acting when a famous German director's wife came to her school to teach children acting, but that she had been absorbed by the performing arts from as far back as she could remember.
"The only thing I ever wanted for my birthday from the time I was old enough to speak, practically, was, 'I'd like to go see a play,'" she recalled.
After studying actor under famed instructor Lee Strasberg, Harris became a well-known figure on the New York stage, including in productions like "Company," "Bad Habits," and "The Tribute Artist."
She made her film debut in 1968's "Isadora" starring Vanessa Redgrave, going on to appear in such films as "Up the Sandbox" (1972), "Tempest" (1982), "Reuben, Reuben" (1983), "Three Men and a Baby" (1987), and "I Do & I Don't" (2007).
Harris's greatest impact was on TV, and she received a BAFTA nomination for her portrayal of Wallis Simpson in 1978's miniseries "Edward & Mrs. Simpson."
After appearing on such series as "The Bob Newhart Show" (1975), "Kojak" (1975), "Three's Company" (1979), "Knots Landing" (1981), and "Archie Bunker's Place" (1981), she took the role with which she would become most closely identified: Sylvia Buchman on "Mad About You" (1993-1999). She appeared on more than 70 episodes, and also reprised her role on two episodes of the show's limited-series 2019 revival, which became her final performances in any medium.
In 1993, she founded the Actors Company Theater, acting as one of its artistic directors until her death.
Married to and divorced from producer Eugene Wolsk, Harris is survived by her partner Nathan Silverstein, her brother and sister-in-law, and nieces and nephews.