Ewan McGregor will join the upcoming Harley Quinn spin-off movie Birds of Prey

According to Deadline, the actor will play crime boss Black Mask. The Gotham Mafioso will be the villain of the Quinn spin-off, squaring off against a gang made up of Quinn, Huntress, and Black Canary. 

Quinn, who began her life as a foil and love interest for the Joker on Batman: The Animated Series, quickly grew into a fan favorite. And Margot Robbie's turn as the madwoman at the side of the Clown Prince of Crime was one of the few redeeming factors of DC's Suicide Squad

Robbie has been pushing hard for the Birds of Prey movie, spending two years pitching the idea and successfully convincing studio heads to make it a more adult affair

"I pitched the idea of an R-rated girl gang film including Harley, because I was like, ‘Harley needs friends.’ Harley loves interacting with people, so don’t ever make her do a standalone film," she said in an interview with Collider. "She’s got to be with other people, it should be a girl gang. I wasn’t seeing enough girl gangs on screen, especially in the action space. So that was always a big part of it."

Robbie's also happy with the fact that DC picked a woman (Cathy Yan) to direct ladies-led action movie. 

"And then of course having a female director to tell that story. And giving a female director the chance to do big-budget stuff. They always get, 'Here’s the tiny little film'… I was like, 'I love action. I love action films. I’m a girl. What, are we meant to only like a specific thing?' So it was a hugely important to find a female director for this, if possible. But at the end of the day—male, female—the best director gets the job and Cathy was the best director," she said.