Yes, he may be the same guy who memorably hit the red carpet arm-in-arm with Britney Spears in a frightful, faded-denim ensemble complete with a denim cowboy hat. But that was then. These days the "The Social Network" star who plays Sean Parker, Napster co-founder and Facebook president, is showing the world how men's fashion is done. More than any particular look, what we love about Justin is that the actor/popstar/restaurateur/designer knows how to turn it out for any and every occasion. "Movie premiere" Justin looks completely different from "fashion week" Justin or "backstage at a Jay-Z concert" Justin. We applaud his versatility as well as his taste for three-piece, slim-cut suits and biker jackets. Herewith a gallery of his go-to looks.WATCH MORE EPISODES OF THE THREAD.