Los Angeles, Feb 1 (IANS): Actor Ewan McGregor says it is very important for an actor to understand the character, adding that "you can't play the bad guy or the good guy" without understanding the heart of the role.

The actor will soon be seen playing the powerful and sinister antagonist Roman Sionis aka Black Mask in upcoming film "Birds of Prey".

In the DC Comics adaptation, Margot Robbie will be back as Harley Quinn along with her gang Mary Elizabeth Winstead's huntress, Jurnee Smollett-Bell's Black Canary, and Rosie Perez's detective Renee Montoya.

"I wanted to work with Margot, and then I saw Cathy Yan's movie 'Dead Pigs' and really liked it. It reminded me of 'Trainspotting' - something new and interesting, so I was excited to work with her as well. But mainly, I just liked the script. The dialogue was clever and very well-written, and I was happy to play the chief villain who's all about control and power and thinks he's so clever and wonderful. But of course, he's a horrible, despicable person," McGregor said.

McGregor feels "it's important for an actor to understand the character".

"You can't play the 'bad guy' or the 'good guy,' you have to play the person and know what makes him tick. In Roman's case, he is an absolute narcissist, which makes him think he can charm anyone, and he has rage issues that come into play, so he loses his temper all over the place. Both were really fun to do," he added.

Warner Bros. Pictures will release the film in India on February 7.