Sirus Black is a Gryffindor at Hogwarts school and a canon character in the Harry Potter books. He in an animagus, having the ability to transform into a black dog- earning him the nickname "Padfoot". He is a close friend to James Potter, Peter Pettigrew and Remus Lupin.
He is the older brother of Slytherin Regulus Black and the only member of his Pureblood family to be sorted into Gryffindor. He adamently opposes their views on Muggle-bornes and support for Voldemort. Because of this they disowned him, and he spent several summers taking residence in the house of James Potter. Eventually, the money left for him by his late uncle Alphard Black allowed him to buy his own flat, though he still took up a summer job at the Leaky Cauldron to support himself.