Spending twelve long years in Azkaban prison for a crime he didn't commit, Sirius "Padfoot" Black is the last heir to the House of Black. Having been first featured in The Prisoner of Azkaban, the third book in the Harry Potter series by J.K. Rowling, Sirius once attended Hogwarts School of Witchcraft and Wizardy with Harry's father. James and Sirius were the best of friends and when Harry was born, his parents named Sirius Harry's godfather. Although at first seeming dangerous and scary, Sirius is a loyal and trustworthy person. He is also an Animagus, a magical talent for turning himself into the form of an animal, in his case a big black dog. Later portrayed by Gary Oldman in four of the Harry Potter films, Sirius Black is a character favorite, particularly because of his close relationship with Harry.