Even for a performer known for his physical transformations, Jared Leto reached another level with “House of Gucci.” To play the foolish and ultimately tragic Paolo Gucci in Ridley Scott’s epic drama, Leto underwent hours of makeup and prosthetic work – and the result rendered him so unrecognizable that even costars like Al Pacino and Jeremy Irons weren’t aware they were initially sharing a set with the Oscar-winning actor.

“You have no idea how mind-blowing it is when this guy came in, dressed as Paolo, stood next to me — I was new in Italy — and I thought, ‘Who is this?,’ because he kept calling me ‘Papa!’” Pacino said last year. “Somebody, a sensitive person in the area, said, ‘Al, it’s Jared.’ I swear to you, I bowed to the floor. I remember, I said, ‘You are an inspiration. I can go on now.’”

“On set, most of the...