This is very sad news. Harold Gould was one of those "Hey, it's that guy!" character actors who could always be counted on to provide an entertaining performance.
Twice, he was cast as the dad in pilots for successful, long-running series, but was replaced when the shows went to air: That Girl and Happy Days. I don't know why he wasn't chosen for Happy Days the series, but I recall a documentary about television several years ago about Jewish actors that specifically stated Gould wasn't chosen for That Girl the series because he was perceived as being too ethnic for Middle America. That makes no sense to me, but there it was.
Some actors can play only certain types effectively. For example, long-time familiar television faces like Lloyd Bochner, Fritz Weaver, Alfred Ryder, Albert Paulsen, and Dan Duryea were always the "secret villain"---if a plot called for a spy, traitor, or sell-out, and one of those actors was in the episode, then he was it. Meanwhile, guys like Clint Walker, Steve Holland, and Doug McClure were doomed to be good guys.
But Harold Gould was one of those versatile actors who could play any part with equal facility. I remember him from God knows how many things, but probably the first one that leaps to my mind was when he played the part of an organised crime family that was literally family, in a three-episode arc of Hawaii 5-O titled "V for Vashon". Over three successive weeks, McGarrett and his team put away first the son, then the father, then the grandfather, running a crime cartel. Harold Gould played the father, Honore Vashon, and he was as chilling and deadly there as he was funny and compassionate as Rhoda's father.
Executives and bums, cops and grifters, Gould could do them all credibly. He was one of that dying breed of perennial television performers---folks like Harold J. Stone, J. Pat O'Malley, Jesse White, John Hoyt, Virginia Gregg, Marlyn Mason, Peter Mark Richmond, Bradford Dillman, Lois Nettleton, Betsy Jones-Moreland---who could play any part handed to them, and yet never seemed to land a regular spot in a hit show. Nevertheless, they were seen virtually every week somewhere on prime-time television.
Actors and actresses like that work their way into the hearts and minds of the audience in a way that even the stars cannot.
He played a small role in Soap, sharing a hospital room with Billy Crystal's character, Jody Dallas, after Jody attempted to commit suicide. It's a testament to Gould's ability that his performance in that bit part has stuck with me all these years.
The part that sticks in my mind is The Sting (I don't remember watching Rhoda). He did have one onscreen role on The Twilight Zone, but it wasn't one of the better episodes, so I had to do some research before I remembered it.