Helmond's talent agency APA announced Friday that she died last Saturday of complications from Alzheimer's disease at her home in Los Angeles.
Nominated for seven Emmy Awards in a 60-year career, Helmond played Judith Light's mother and Alyssa Milano's grandmother Mona Robinson on "Who's the Boss?," the series that ran on ABC from 1984 to 1992.
She played matriarch Jessica Tate on another ABC sitcom, "Soap," a parody of soap operas that aired from 1977 to 1981.
Helmond was a favorite of director Terry Gilliam, appearing in his films "Brazil," ''Time Bandits" and "Fear and Loathing in Las Vegas."
She was born in Galveston, Texas before moving to New York, Los Angeles and London to pursue acting.
Friday, Helmond's TV granddaughter Alyssa Milano paid tribute to the actress on Twitter, remembering her as "funny, gracious, compassionate."
Katherine Helmond has passed away.— Alyssa Milano (@Alyssa_Milano) March 1, 2019
My beautiful, kind, funny, gracious, compassionate, rock. You were an instrumental part of my life. You taught me to hold my head above the marsh! You taught me to do anything for a laugh! What an example you were!
Rest In Peace, Katherine. pic.twitter.com/HNIH0Ty6MN
The Associated Press contributed to this report.