Margot Robbie 'Excited' for Lady Gaga's Harley Quinn in 'Joker: Folie á Deux' (Exclusive)

ET spoke to Robbie at the premiere of her new film, 'Babylon,' about passing the baton to Gaga for the 'Joker' sequel.

Margot Robbie couldn't be more excited to see Lady Gaga step into the role of Harley Quinn in the upcoming Joker sequel. ET's Kevin Frazier spoke to Robbie at the premiere of her new film, Babylon, where she opened up about passing the baton to Gaga for Joker: Folie á Deux.

"I think she's going to do an amazing job. I'm so excited, it's all I could've ever hoped for Harley was that she would become one of those characters, kinda like Batman or Hamlet, that's gets handed from actor to actor, everyone gets a go at playing them," She said of Gaga taking on the role of Quinn in the DCEU's musical spin on the Joker franchise. "So, I think it's just credit to her as a character that people want to see her in multiple iterations. I'm excited."

While Robbie, who has starred as Quinn since 2016's Suicide Squad, won't be returning as the iconic villain, she's stepping into the shoes of an even more iconic character in Barbie.

Despite a snippet of the trailer leaking ahead of Thursday night's premiere, a full teaser trailer is due out Friday with Robbie telling fans to be prepared to see it in all its "glory."

"It feels like anything that happens gets a huge reaction for Barbie," she added. "It's exciting."

In Robbie's latest film, she stars as Nellie LaRoy, an unpredictable up-and-coming starlet searching for fame. And just like her character, she snuck in an unexpected moment of her own when she planted an unscripted kiss on her Babylon co-star, Brad Pitt.

The kiss ultimately got the OK from the film's director, Damien Chazelle, and it passed the test for Pitt too, who told ET that there's always room for "character interpretation."

"We all established our boundaries before making this movie," Robbie assured, "because it's a movie that really pushes boundaries in a lot of ways."

"We're all good," she added.

See Robbie in Babylon when the film hits theaters Dec. 23.