She got the part by appearing in a multi-episode stint as "Ingrid Svenson", birth mother of Corinne Tate (Diana Canova), on the TV sitcom Soap. She also appeared as northern matriarch Maude Hazard in the acclaimed mini-series North and South in 1985 and again in 1986.

Earlier in her career, Swenson had a notable turn on the TV western series Bonanza in two episodes: "Inger, My Love" (1962) and "Journey Remembered" (1963). Swenson took a brief leave of absence from her starring role in 110 in the Shade on Broadway to appear in "Journey Remembered." The appearances were significant in that she played Lorne Greene's Ben Cartwright character's second wife, the mother of Hoss Cartwright, played by Dan Blocker, She was actually four years younger than Blocker. After Bonanza ended its 14-year run, Swenson guest starred in an episode of Lorne Greene's short-lived crime drama Griff.

Also early in her career Swenson had supporting roles in the films Advise and Consent (1962) and The Miracle Worker (1962) in which she played Helen Keller's mother.

A life member of The Actors Studio, Swenson is a trained lyric soprano  and starred on Broadway in New Faces (c. 1956), The First Gentleman(1959) and received Tony Award nominations for Best Actress in a Musical for her performances in 110 in the Shade (1964) and Baker Street (1965).

Swenson is married to sound editor Lowell Harris, with whom she had two sons, James (deceased) and Mark.

Though her Swedish-sounding name and trademark (German) accent on Benson suggest otherwise, she was born and raised in the U.S., and normally speaks with an American accent.

Source: Wikipedia