The seven-episode limited series from producers Ryan Murphy, Ian Brennan and Janet Mock embraces the elegance and mystery of the film industry’s post-World War II golden era while imagining an alternate ending in which women, people of colour, the LGBT community and others who had been marginalised get the leading roles, literally and figuratively, that many are still being denied.

Parsons, 47, likes the “bittersweet” imagining of what Hollywood might be like if the events portrayed in Hollywood had occurred nearly 80 years ago.

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“As somebody who’s part of the business now, it’s very evident how eager and desirous most of Hollywood, in my opinion, is to tell stories that haven’t been told from people that we haven’t seen yet,” says Parsons, whose career happily did not suffer when he came out as gay during the Big Bang run.

“Once you watch some of these brave choices being made in the ’40s, the mind reels in that fantasy of what life would look like now had this happened then. It’s a real call to not feel overly satisfied about where we are now.”

Parsons took on the creepy, corrupt Willson at the behest of Murphy, after they worked together on HBO’s 2014 adaptation of The Normal Heart and Netflix’s remake of The Boys in the Band, due later this year.

He did not know much about Willson, who created his “own little [talent] factory, pumping out those milk-fed all American hunks with quick names like Rock, Guy and Tab”, Parsons says. Hollywood also portrays a seamier side of Willson, as the agent employs blackmail and mob connections to get his way and demands sexual favours from handsome young actors.

“He was such a complicated, colourful, outlandish character, and despicable in many ways, that he’s the kind of person that it would be easy to lump into a category” as a black-and-white villain, Parsons says. “I knew I was going to have to do my best to make him sound believable and find legitimate [or] empathetic reasons he might do the things he does.”

That included the kind of sexual harassment that has cost several contemporary Hollywood power players their jobs with the rise of the #MeToo movement. In Hollywood and in the real industry at that time, casting-couch behaviour was rampant, although Willson likely was judged more harshly because he was gay, Parsons says.

Murphy thought Willson was just the role to set Parsons on a dramatically different path after Big Bang.

“I call this Jim’s Mary Tyler Moore moment. Jim is a brilliant actor and I think so many people just think of him as Sheldon. Mary Tyler Moore, when she finished her sitcom, went and did Ordinary People, America’s sweetheart suddenly becoming America’s villain,” Murphy says.

“I just thought Jim would kill this part. He got to wear false teeth and a bald spot and he got to be [a character] he’s never done. I think it was very liberating for him.”

Parsons agrees: “I can only describe it as being a kid in the candy store as an actor. It offered me the opportunity to see how hungry I was to play something different.”

Parsons maintains ties to his Big Bang colleagues. He is an executive producer and the narrator of spin-off Young Sheldon. And he’s producing a Fox comedy, Call Me Kat, starring his former co-star Mayim Bialik, who played Sheldon’s wife, Amy Farrah Fowler.

He does not miss making Big Bang, but a year after taping the finale and amid a coronavirus quarantine, “it has made me realise the hollow part of not seeing so many people for so long”, he says.

“You take it for granted when you’re with them most days for nine months a year for 12 years, and then they’re suddenly just not part of your orbit any more.

“I think of that now, because I have a lot of time to think about it.”