Mickey Rourke was chosen for the role of Iron Man's enemy Whiplash in the second movie of the series. The character was a Russian scientist and a former prisoner, so the actor did a lot of preparing for the role, even though he didn't really get along with Marvel and they didn't consider his suggestions about how he would like to portray Whiplash.
He went to a Russian prison to see what it looked and felt like. He also was very interested in the inmates' tattoos. On top of that, he was studying the Russian language every day for three hours. He trained not only his mind but also his body to achieve the menacing strong villain look.