LOS ANGELES -- Helen Mirren is oddly absent from the Harry Potter film franchise that proved close to a full-employment act for Britain's acting greats. But she's found her own path into its magical world.Dame Helen, as the Oscar, Emmy and Tony-winning actor is properly addressed, makes her debut as a quiz host with “Harry Potter: Hogwarts Tournament of Houses.” The weekly, four-part series begins 8 p.m.