The star of The Fighter and Ted was asked by Yahoo! if there were any roles he coveted - and was quick to respond.
"I would like to take over the Iron Man franchise for Robert Downey, [but] it's one of those things where I kind of like playing real people, [so] I've never been asked.
"Once I was kind of being talked about for the Robin role in Batman... somebody dodged a bullet!"
The film he was referring to was 1995's Batman Forever, starring Val Kilmer as the caped crusader and Chris O'Donnell as Robin.
Downey Jr.'s four-movie deal to play Iron Man/Tony Stark expired with Iron Man 3 - but he is believed to have now committed to play the character in at least another two Avengers movies.
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