Sirius Black is a fictional character in J. K. Rowling's Harry Potter series. Sirius was first mentioned briefly in Harry Potter and the Philosopher's Stone as a wizard who lent Rubeus Hagrid a flying motorbike shortly after Lord Voldemort killed James and Lily Potter. His character becomes prominent in Harry Potter and the Prisoner of Azkaban, in which he is the titular prisoner, and is also revealed to be the godfather of the central character Harry Potter. He is portrayed in the film adaptations by Gary Oldman. Source: Wikipedia (en)