There's plenty of body horror going on in L.A.'s cosmetic-surgery wards, but David Cronenberg's latest film is more concerned with the city's mentally disfigured. Julianne Moore stars as a monstrous fading star who makes Norma Desmond and Baby Jane look rational, while Robert Pattinson, John Cusack, and Mia Wasikowska round out a cast of showbiz grotesques. For a proud Canadian like Cronenberg, Hollywood can pose a philosophical quandary. ''There, it's not enough to physically exist,'' says the director, who debuted the film at May's Cannes Film Festival. ''You need a career, otherwise you can die a pre-death.'' Is any phrase more fraught than ''You're a nobody''?