Actor of the year: Forest Whitaker

Director Kevin Macdonald terms the casting of Whitaker as Idi Amin Dada in “The Last King of Scotland” as “the best decision I made.”

The irony is that Macdonald, an Oscar-winning documentarian for “Five Days in September,” had been scouting Europe and Africa without success before he came to L.A. He was reluctant even to see Whitaker, whom he thought “too gentle” to play the strongman whose mad, paranoid rages left 300,000 dead.

“I understood his trepidations,” says the actor. “It’s his first (fictional) movie. It’s a big deal. If this character doesn’t work, then obviously the film isn’t going to work.”

So, despite his extensive and varied credits, Whitaker gladly performed a scene in Macdonald’s office.

Whitaker, for his part, wasn’t interested in Amin if he couldn’t find the man behind the monstrous image. “I didn’t approach it either liking him or disliking him,” he says. “I approached it as a way to figure him out, figure out how he felt about things, his passions and pains.”

Over six months, Whitaker studied Swahili (“Because it was really important”) and learned to play the accordion. Not content with extensive footage, he visited Amin’s hometown where he met his brother, sister, generals, girlfriend and ministers.

“You just start to accumulate these different things and the memories start to become your own in a way, because you’re experiencing them too,” he says. “You’re eating his food and it becomes a part of you.”

Following an acclaimed turn on “The Shield” last season, Whitaker suddenly finds himself with a new, tougher image. “Certainly the guy on ‘The Shield’ is not cuddly and I don’t think there is anything soft about ‘Ghost Dog.’ But maybe people will recognize that my capabilities are maybe more vast.”

Follow @Variety on Twitter for breaking news, reviews and more