The Obi-Wan Kenobi actor told the Hollywood Reporter he was interested in the role as soon as director Dan Minahan showed him pictures of Halston and his entourage. “I could tell instantly from the photos: I wanted to play him. Just something about the way he holds himself, something in his eyes,” McGregor said. After officially signing on to the project, McGregor dove in. He sat in on pitch meetings, studied footage of the designer, met with Liza Minnelli herself, and even worked with the show's costume designer to learn how to sew. Minahan told the Hollywood Reporter, “When you see him make the dresses in the show, he’s literally cutting the fabric, pinning it, and making it.”
But some people, including Billy Porter, were critical of the decision to cast McGregor–who identifies as heterosexual–as the openly gay Halston. In his interview with The Hollywood Reporter, McGregor expressed that he understood and respected the criticism, but stood by the casting. “If it had been a story about Halston’s sexuality more, then maybe it’s right that gay actors should play that role,” he said. “But in this case — and I don’t want to sound like I’m worming out of this, because it’s something I did think a lot about — I suppose ultimately I felt like it was just one part of who he was.”
“There are people I met who do not have nice things to say about him. And there are people who love him and are unbelievably loyal to this day. I was excited to play that. To go to the extremes of his temper,” McGregor said in the interview.