Licorus Black

Mr. Black was a wizard, as well as the earliest known member of the pure-blood House of Black. He married a pure-blood witch and is the earliest known ancestor of the Black family, being depicted on the Black family tree tapestry that hangs in the ancestrial home of 12 Grimmauld Place. It's possible that he is the brother of Alexia Walkin, Phoebe and Eduardus Limette Black.

Biography
Black was born to the House of Black, possibly in the 1820s, to unknown pure-blood parents. He seems to have had three siblings; Alexia Walkin, Phoebe, and Eduardus Limette Black. Mr. Black was raised in a household that strongly believed in the importance of blood purity, and as such likely carried a grudge against Muggle-borns, whom most of the family called Mudbloods. His brother Eduardus was disowned for unknown reasons, which likely had an effect on him.

At the age of eleven, Black presumably began his schooling at Hogwarts School of Witchcraft and Wizardry, where he may have been Sorted into Slytherin House.

Sometime after completing his schooling, Black married a pure-blood witch, with whom he seems to have had several children; a daughter, who married into the Blishwick family by being wed to Jimbo Blishwick, Arcturus, and Cygnus Black. He apparantly died after this point.

Behind the scenes

 * Based on a statement by Horace Slughorn, this character may have been a member of Slytherin house. However, Black attended Hogwarts in the 1830s, long before Slughorn was even born.
 * This character appears only on the version of the Black family tree shown in the film adaptation of Harry Potter and the Order of the Phoenix. He was not included on the version of the tree which J. K. Rowling gave to a charity auction in 2006 . However, according to director David Yates, Rowling provided the filmmakers with a copy of the Black family tree going back eight generations . The filmmakers presumably received a more complete version of the tree than the one auctioned off, which only goes back six generations.
 * This character is decipted as the first Black on the family tree seen in the film adaptation of Harry Potter and the Order of the Phoenix, but in the novel, Harry notes that the family tree dated back (as far as he could tell) to the Middle Ages, implying that Mr. Black is not truly the earliest member of the family.
 * Except for the colour of his hat, this character's picture on the family tree bears a striking resemblance to that of Pollux Black. This was likely done by the film-makers to save time, as other characters, such as Elladora and Callidora Black also have images that are remarkably similar.