'Benson' Star Inga Swenson Dead at 90

Inga Swenson, famous for her work in the early 1980s ABC sitcom "Benson," is dead.

The actress died Sunday night in Los Angeles as a result of natural causes ... her son, Mark, tells TMZ.

Inga's son says her husband, Lowell Harris, was with her when she died at a board and care facility. We're told Inga's heath had been in decline for the past 6 months, so her death did not come as a shock to the family.

Inga famously played German cook Gretchen Kraus on "Benson" ... appearing in over 150 episodes over seven years and earning three Emmy nominations for her work.

"Benson" was a spin-off of another TV sitcom, "Soap," where Inga had a multi-episode role as Ingrid Svenson.

In addition to "Benson," Inga also starred on Broadway ... and her performances as Lizzie Curry in "110 in the Shade" and Irene Adler in "Baker Street" resulted in two nominations for the Tony Award for Best Actress in a Musical. She's a trained lyrical soprano.

Inga acted in two movies in 1962 ... with a pair of supporting roles in "Advise and Consent" and "The Miracle Worker," where she plays Helen Keller's mother.

She married Lowell, a sound engineer, in February 1953, and the couple had two children, one of whom already passed away ... and in 1998 she retired from Hollywood.

We're told she wanted to be cremated and have her ashes buried with her late son in San Rafael, CA.

Inga was 90.