Sirius Black III is the godfather of Harry Potter. He is the son of Walburga Black and is the most unpopular to his family because he was a muggle lover or "Blood Traitor" as they like to call it, and all the Black Family were pure-bloods as in the nasty version (calling M
Sirius Black

Sirius in 1995 in a Meeting with the Order of the Phoenix

uggle Born's mudbloods) except him. He was wrongly accused of betraying his friend James Potter and his family.