HBO has officially cast one of the major characters in the second season of its upcoming “Harry Potter” adaptation. His casting comes months before audiences will even see the first season of HBO’s ambitious “Harry Potter” reboot. The character Lockhart is first introduced in the second “Harry Potter” novel, replacing Quirinus Quirrell as the Defence Against the Dark Arts professor. ‘Harry Potter’ Season 2 Continues To Move ForwardCasting news for the second season of HBO’s series may be surprising to some considering that the first season has yet to air. Fiennes played the Dark Lord throughout the original film franchise, beginning with “Harry Potter and the Goblet of Fire.”