In the early-1990s I was at a party in Hollywood talking with the most amazing looking guy. He was a male prostitute, not a street level guy but a high priced call boy, I guess you would call it. He told me one of his clients was a real freak, with a torture dungeon set up in his home, and the guy was a famous TV star but the trick refused to reveal his name.
I said, "Give me a hint." He indicated, "the person starred in two TV series at the same time in the 1970s, one a drama and one a comedy." I thought of Robert Reed immediately who was on The Brady Bunch and Mannix at the same time. His reaction didn't give anything away (he was a prostitute, after all, the original poker face) but I can't think of any other TV stars that fit that description... can you?