Harry Potter (film series) to be re-cast for the third instalment, "Harry Potter and the Prisoner of Azkaban". David Heyman and director Alfonso Cuarón chose Michael Gambon to portray the character of Dumbledore, which he did for all succeeding films. Notable recurring cast members include Helena Bonham Carter as Bellatrix Lestrange, Warwick Davis as Filius Flitwick, Ralph Fiennes as Lord Voldemort, Brendan Gleeson as Alastor Moody, Richard Griffiths as Vernon Dursley, Jason Isaacs as Lucius Malfoy, Gary Oldman as Sirius Black, Fiona Shaw as Petunia Dursley, Timothy Spall as Peter Pettigrew, David Thewlis as Remus Lupin, Emma Thompson as Sybill Trelawney, Mark Williams as
Harry Potter and the Prisoner of Azkaban (film) and Sirius. The present Harry realises that it was actually him who conjured the Patronus, and does so again. Harry and Hermione rescue Sirius, who escapes with Buckbeak. Exposed as a werewolf, Lupin resigns from teaching to prevent an uproar from parents. Sirius sends Harry a Firebolt broom, who happily takes it for a ride. With "Prisoner of Azkaban", production of the "Harry Potter" films switched to an eighteen-month cycle, which producer David Heyman explained was "to give each [film] the time it required." Chris Columbus, the director of the previous two films, decided not to return to helm the