Marc Jacobs, the brash enfant terrible of high fashion, can’t seem to do anything without making a splash. Since he became creative director of luxury French fashion house Louis Vuitton, he has strengthened its business, breathing life into the formerly stuffy leather goods company with a now-iconic collaboration with Japanese artist Takashi Murakami. His own lines, Marc Jacobs and Marc by Marc Jacobs, have become a wardrobe staple for millions of women (try to walk a Manhattan mile without spotting one of his trademark workwear bags). His retail mecca on Bleecker Street, which he runs with his partner, Robert Duffy, has transformed Greenwich Village, turning the neighborhood into a fashion haven. Add to this his activism on issues from AIDS to skin cancer—who can forget those T-shirts featuring naked celebrities?—and it becomes readily apparent that Mr. Jacobs is a whole lot more than just the name on your bag.