Was Sirius Black the uncle of Draco Malfoy?

As we can see from the flow chart from 'Pottermore' Cygnus Black III is the maternal grandfather of Draco Malfoy and is also the brother of Walburga Black and Walburga is the mother of Sirius Black. So, Narcissa Black is a cousin of Sirius Black. read more

Yes, Sirius Black was uncle of Draco Malfoy. Since, the Malfoy and Black were all about pure blood and stuff, they also married in pure bloods. Narcissa, cousin of Sirius and Regulus Black married Lucius Malfoy. read more

As pointed out, Sirius Black was actually Draco’s first cousin once removed - not his uncle. That being said, according to J.K. Rowling, yes, Harry Potter and Draco Malfoy are related - albeit distantly - by marriage, if not by blood. read more

Sirius Black is Draco Malfoy's first cousin once removed. According to an answer in Quora: Since, the Malfoy and Black were all about pure blood and stuff, they also married in pure bloods. Narcissa, cousin of Sirius and Regulus Black married Lucius Malfoy. And at this answer. read more