The star died on Wednesday (04May11) in Danbury, Connecticut.
Thompson launched her career on the stage in the 1950s, making her Broadway debut in 1959 musical Juno. She went on to portray multiple characters in the play Twigs, which landed her a Tony Award in 1972.
But she was perhaps best known for her role as TV matron Kate Lawrence on U.S. drama series Family, a role which earned her the Emmy for Outstanding Lead Actress in a Drama Series in 1978. Her performance on the show also garnered her three Golden Globe nominations.
Her other TV credits include appearances on legal drama Owen Marshall, Counselor at Law, Father Dowling Mysteries, hit sitcom Cheers and crime drama Law & Order.
Thompson's last screen role came in 2000 movie Pollack alongside Ed Harris.
She is survived by her husband of 61 years, Donald Stewart, and their daughter Liza Sgueglia, reports the New York Daily News.