Lady Gaga‘s casting as Harley Quinn for the upcoming Joker sequel, Folie à Deux.The singer will star alongside Joaquin Phoenix in the new film, which will reportedly be a musical. Robbie previously portrayed the character in three, unrelated DC films: Suicide Squad, Birds Of Prey and The Suicide Squad.Speaking of Gaga’s casting, Robbie told MTV News in a recent interview: “It makes me so happy because I said from the very beginning, all I want is for Harley Quinn to be one of those characters, the way like Macbeth or Batman always gets passed from great actor to great actor.”Robbie went to explain how she doesn’t feel female characters are afforded the same treatment, although she did acknowledge that she was able to portray Queen Elizabeth I after Cate Blanchett.“It’s such an honour to have built a foundation strong enough that Harley can now be one of those characters that other actors get to have a go at playing,” she added.