Sirius Black

Sirius Black, nicknamed Padfoot, is the last heir of the House of Black, a once notable pure-blood Wizarding family. He rejected his family's pure-blood elitism and reverence for the Dark Arts. In contrast to his home life, Sirius greatly enjoyed life at Hogwarts (being the only Black to be sorted into Gryffindor), where he was inseparable from his best friend James 'Prongs' Potter and befriended Remus 'Moony' Lupin and Peter 'Wormtail' Pettigrew. Sirius, along with James, bullied Snape while they were at school. Sirius left home at the age of sixteen and took refuge with James and his parents. His outraged mother burned his name off the family tree, but he was left financially independent by his Uncle Alphard's generous bequest (hence Alphard's name being burnt off as well). After leaving school, he remained close friends with James and eventually attended James and Lily's wedding as best man. When Harry was born, the Potters name Sirius as his Godfather. When the Potters went into hiding from Voldemort, Sirius suggested they use Peter Pettigrew as Secret-Keeper, believing that Voldemort would not suspect Pettigrew and would hunt Sirius instead. However, Pettigrew betrayed James and Lily, and they were murdered by Voldemort. Sirius tracked Pettigrew down, but during the confrontation Pettigrew faked his own death and killed twelve Muggles, framing Sirius for betraying the Potters and murdering Pettigrew and the Muggles. Sirius was arrested and sent to Azkaban without trial. Unlike most of the other Azkaban prisoners, Sirius was able to keep his sanity as he knows he is innocent.

Twelve years later, Sirius sees a picture of the Weasley family on the front cover of the Daily Prophet, in which a rat stands perched on Ron's shoulder. The rat is Ron's pet, Scabbers, and Sirius immediately recognises Pettigrew in his Animagus form. This knowledge clears his mind and enables him to escape Azkaban, accomplishing this feat by transforming into his Animagus dog form; his severe weight loss from malnutrition and the Dementors' lack of ability to differentiate between unsophisticated canine feelings and insanity allows him to slip through his cell bars. After his escape, Sirius takes refuge in and around Hogsmeade. Knowing that the Dementors are stationed around Hogsmeade and at Hogwarts, Sirius remains in his Animagus form during this time, and is able to enter the Hogwarts grounds without being detected by the Dementors. He makes several unsuccessful attempts to kill Pettigrew, until his presence is detected by the students and teachers of Hogwarts and the school's security is increased. Towards the end of Prisoner of Azkaban, Harry, Ron, and Hermione confront Sirius and Harry attempts to kill him. Lupin, however, who has learned that Sirius is innocent, prevents Harry from doing so. Scabbers is unmasked as Pettigrew, and Harry begins to view Sirius as a surrogate father, although events swiftly turn against him again –Pettigrew escapes, and Sirius is captured by the Dementors at Hogwarts and sentenced to the "Dementor's Kiss". Harry and Hermione help him escape with Buckbeak, a hippogriff who had also been unjustly condemned.

In Harry Potter and the Goblet of Fire, Sirius advises Harry on how to complete the Triwizard Tournament tasks. In Harry Potter and the Order of the Phoenix, he takes refuge in his ancient family home at 12, Grimmauld Place, which he allows to be used as the Order headquarters. His confinement causes depression, and he is frequently withdrawn and antagonistic. When he briefly leaves the house to see Harry off to Hogwarts, his Animagus form is recognised by Draco and Lucius Malfoy, resulting in more threats and warnings. Sirius acts as an older brother figure to Harry throughout the book but, according to Rowling, "what Harry craves is a father." Sirius encourages Harry to oppose Dolores Umbridge and her reforms, and strongly approves of Harry starting the secret defensive tutorial group for students, Dumbledore's Army. He also demonstrates a high-level of trust in and respect for Harry, willingly answering his questions about the Order and Voldemort. With his growing power, Voldemort implants a false vision into Harry's mind that Sirius is taken captive and under torture at the Department of Mysteries. Convinced that Voldemort is torturing Sirius, Harry and his friends gain access to the Department of Mysteries. When they are ambushed by Death Eaters, Harry realises that Voldemort has lured him into a trap. Snape, however, alerts the Order that the students have gone to the Ministry after confirming that Sirius is safe at Grimmauld Place. Several Order members arrive at the Ministry, Sirius among them, and battle the Death Eaters. During a frenzied duel with his hated cousin Bellatrix Lestrange, Sirius taunts her for failing to harm him. Bellatrix strikes Sirius with a curse, sending him backwards into a veil in the Death Chamber and thus causing his death, from which Harry finds it hard to recover. Sirius's will stated that his possessions, home and house-elf Kreacher are to be inherited by Harry.

Sirius makes a final appearance toward the end of Harry Potter and the Deathly Hallows when he is summoned by the Resurrection Stone along with James, Lily, and Remus Lupin to help Harry walk through the Forbidden Forest and sacrifice his life to Voldemort.

Sirius was portrayed by Gary Oldman in the film adaptations of Prisoner of Azkaban, Goblet of Fire, Order of the Phoenix, and Deathly Hallows. Sirius as a teenager made a brief appearance in Order of the Phoenix (played by James Walters), and is also slated to appear in Deathly Hallows, to be portrayed by Rohan Gotobed.