How do you portray genius on the screen, if all you have to work with are gifted, but ordinary, humans? If the genius is a real person -- a Mozart, Beethoven or John "A Beautiful Mind" Nash -- the job becomes fairly straightforward: Cast an actor who can suggest the original subject physically and emotionally. Add samples from the original's work (operas, symphonies, equations) and -- voila.
But what if your genius is based on a comic-book character? One approach is that of Kenichi Matsuyama, who played the "genius" detective L in the two "Death Note" films as a study in eccentricity, with his languorous manner, pasty face, kohl-rimmed eyes and ever-present sweets.
Matsuyama's performance was not only the best thing in the films -- but started something of a fad, with fans dressing up as the character, complete with an all-day sucker, for Halloween last year.