Diagnosing Jack Nicholson

The Character: Robert Eroica Dupea
The Diagnosis: Bipolar disorder
The Symptoms: Born into a well-bred family of musicians, Dupea is chronically restless and angry. He flees responsibility, routine, and commitment; he selects an intellectually inferior mate and picks a fight with a surly waitress -- who refuses to bring him toast -- in order to prove his brilliance.
The Prognosis: Dupea's anger could be helped with lithium. A date with Angie Dickinson wouldn't hurt.

Five Easy Pieces, Jack Nicholson, 1970. Courtesy of the Everett Collection.