The star passed away on Saturday (11Sep10) at the Motion Picture and Television retirement community in Woodland Hills, California, his spokeswoman Jaime Larkin has confirmed.
In a career spanning almost 50 years, Gould starred in over 300 TV shows and a string of movies, including 1973's The Sting, in which he portrayed Kid Twist, and more recent hits Patch Adams and Freaky Friday.
But he was perhaps best known for his role as Betty White's boyfriend on The Golden Girls and as Valerie Harper's father, Martin Morgenstern, on hit 1970s sitcom The Mary Tyler Moore Show and its spin-off Rhoda.
Paying tribute to her former TV co-star, Betty White tells the Los Angeles Times, "He was such a fine actor and such a lovely man. He will be sorely missed."
Meanwhile, his TV daughter Harper told the publication, "Harold brought an extraordinary humour, class, grace and a twinkle to create the character of Martin Morgenstern. He was a friend as well as a co-worker.
He was one of the loveliest gentlemen - and so funny and so good at what he did."
Gould's last TV job saw him join the cast of Nip/Tuck for one episode, while the former drama teacher was also known for his extensive theatre career.
He was also cast as Howard Cunningham in Love & Happy Days, the show that was to become beloved sitcom Happy Days, but was forced to quit the show due to a scheduling conflict..
The star, who earned five Emmy Award nominations throughout his lifetime, is survived by his wife of 60 years, Lea, and his children Deborah, Joshua and Lowell.