During the final seasons of Sex and the City, he dispensed brutally honest advice as Charlotte's gay spitfire pal Anthony Marentino. In his stand-up comedy act, he mercilessly zings the likes of Liza Minnelli and Michael Jackson. Now Mario Cantone is bringing his manically funny, rage-filled riffs to Broadway in Assassins, Stephen Sondheim's darkly comic musical about real-life presidential assailants. Cantone stars as Samuel Byck, the deranged tire salesman who, in 1974, tried to hijack a plane and crash it into the Nixon White House. (He ended tip killing himself during the botched takeover of the plane.) Byck is also the actor-comedian's weightiest role yet. "I wear padding, because he was fat," says Cantone, 44, who jokes," I wasn't about to lose my washboard abs for the show, no way!" Cantone (who lives in Manhattan with his longtime partner Jerry Dixon) is still most famous for his colorful turn on Sex and the City. "People stop me on the street and ask, 'Are you sad it's over?' I miss it. I really do," says Cantone, a Boston native who spent two decades in theaters and comedy clubs before Sex and the City raised his profile. "I worked hard for my semifame."