In a very short time Robert Downey Jr has gone from being one of Hollywood’s most controversial characters to being the face of the summer (albeit from behind an iron mask). His blockbuster Iron Man was a big hit in what was a so-so summer season, and now the actor changes genre (and race!) to play method actor Kirk Lazarus in Ben Stiller’s new film, Tropic Thunder.

ENTERTAINMENTWISE: You’re character Kirk Lazarus (who spends most of the film in-character as Sgt. Osiris) is very reminiscent of a lot of Hollywood’s more serious actors. Was there anyone specifically in mind when you were developing the part?

ROBERT DOWNEY JR.: Well I’ve got people I admire. I think Oriris came out of a phoner I had with Ben while I was shooting Iron Man, he just rang up to make sure I was working on my character. So I spoke in Osiris’ voice and he was laughing and said “that’s really funny.” As for Kirk Lazarus, I like Colin Farrell, Daniel Day-Lewis, Russell Crowe… It’s sort of an amalgam, it’s an alloy of those guys.

EW: Kirk Lazarus’ Australian accent and violent nature makes some obvious parallels with Russell Crowe, what does he think about it?

RD: He’s fine with it, I know that for a fact!

EW: You’re character says in the trailer that he never breaks character until he’s finished the DVD commentary. Did you do the same?

RD: Luckily right before we did the DVD commentary I remembered what I promised in the movie, and so yes the commentary is Osiris primarily, and then when he unmasks he is Kirk Lazarus, and then when the credits are rolling I can just be myself.

EW: Finally, can you tell us anything about your upcoming role as Sherlock Holmes?

RD: Yeah, it’s a pretty strong story, Guy Ritchie is directing, Joel Silver producing- I can’t wait, it’s so exciting! I think besides Chaplin, this will be the most iconic thing I’ve ever done. Then of course there’s Iron Man 2, need I say more? I’m on fire! When you’re hot you’re hot!

Tropic Thunder is released on 19th September.