PRISONER: Ryan O'Reily ( Dean Winters )

CRIME: Stole a car while on a crack binge and ran over a couple of construction workers; given a life sentence after confessing to having his brother kill the doctor's husband.

TELLTALE TRAIT: One word: "Survival," says Winters. "Ryan knows that to stay alive and stay ahead, he can't make friends. He's got to be a lone wolf."

PRIOR RECORD: "I guested on Homicide, NYPD Blue, Millennium, and New York Undercover, and that was a great training ground, but Oz is my baby," says Winters. "I really get to flex my muscles as an actor."

BADASS FACTOR: 4 "Ryan really utilizes his street smarts," says Winters. "And now that he's in for life, he's got nothing to lose."