'Bombshell' star Charlize Theron says Megyn Kelly makeup job 'surpassed what I was hoping for'

Fifteen years after winning an Oscar for playing serial killer Aileen Wuornos in Monster, Charlize Theron is once again utterly unrecognisable as Megyn Kelly in Bombshell. The new drama is about the culture of sexual misconduct and harassment at Fox News that led to the downfall of the network's then-chairman and CEO, Roger Ailes (John Lithgow).

Locking in that stunning transformation was a months-long process, though, for Theron (who is also a producer on the film), makeup artist Kazu Hiro and the production team.

"We did a lot of tests to make sure we were on the right path, so it wasn't like I waited months and then saw myself for the first time," Theron told Yahoo Entertainment (watch above).

"It was quite a process, and where we started and where we ended up was just exponentially [improved]. … It so surpassed what I was hoping for. And Kazu Hiro gets all the credit for that. He knocked it out of the park. His work is flawless in this film."

Lithgow admitted he was also skeptical of roles requiring heavy prosthetics, but was also won over by the skills of Hiro, who won an Oscar two years ago for turning Gary Oldman into Winston Churchill in Darkest Hour.

Read more: The most incredible actor transformations of 2019

"Boy, did he ever bring me around," Lithgow said. "As soon as he put that face on I was like, 'Wow, give me more.'"

Their costar Margot Robbie looks very much like Margot Robbie in the role of Kayla Pospisil, but there's a good reason for that: the character is a fictionalised composite of Fox News staffers. Although she didn't need to sit in the makeup chair for hours, the 29-year-old Australian said she was struck by the subject matter and determined to humanise their plight.

"I had a lot of research to do," she said. "Fortunately — unfortunately, I should say — there are so many accounts of what women have experienced, not just at Fox News but various workplaces around the world. So there was a lot to read.

"And I also feel like I've been having these conversations my whole life, with people who've experienced sexual harassment, not necessarily at the workplace but anywhere. It doesn't take a whole lot of imagination to understand how horrific that could feel when you are standing in that office with Roger Ailes."

Bombshell is in UK cinemas from 17 January. Watch a trailer below.