Sesame Street, even before The Mickey Mouse Club, in the earliest days of television, kids (and adults) rushed home every afternoon to see the adventures of Kukla, Fran, and Ollie, two puppets and their human host. They may never have realized that there was a hunky 30-year old man behind the set, manipulating the puppets and providing their voices.
They certainly never knew that he was gay.
Born in 1917, Burr Tillstrom began the art of puppetry in college, and created the perpetually-surprised Kukla in 1936. Other characters followed, but it was the laconic Ollie (Oliver J. Dragon) who became the clown in the comedy team, a formula that extended from Laurel & Hardy to Martin & Lewis, Abbott & Costello, and in children's tv, Rocky & Bullwinkle.
Themes and storylines were compelling, and not necessarily for kids. They performed mysteries, science fiction, and even the Gilbert & Sullivan operetta The Mikado, with Kukla as Nanki-Poo, Ollie as Ko-Ko, and Fran as Yum-Yum.
The program drew many adult fans, including Orson Welles, John Steinbeck, Lillian Gish, James Thurber, Judy Garland, Talulah Bankhead, and Broadway composer Stephen Sondheim, who wrote Kukla and Ollie a song, "The Two of You."
Tillstrom died in 1985, before gay identity was regularly acknowledged, so his New York Times obituary and his Wikipedia entry both keep him closeted. But the gay communities of Chicago and Saugatuck knew. In 2013 he was inducted in to the Chicago Gay and Lesbian Hall of Fame.
By the way, gay people seem particularly drawn to puppeteering, perhaps because they often live in a world of masks. Here's a link to a "It Gets Better" article for gay youth interested in the art.
And a link to Mark Milano's site on Burr and the whole Kuklapolitan phenomenon.