It was the second Darrin Stevens (Dick Sargent) who was gay. So was Robert Reed ("Mike Brady".) However, I don't know about Alice (Ann B. Davis.) Nancy Kulp (Jane Hathaway) on "The Beverley Hillbillies" was also gay. Someone I was surprised to learn about was Raymond Burr. It wasn't obvious with him.
Another screen "heartthrob" who kept in the closet for a long time was Richard Chamberlain. Remember him?