Pollux Black

Pollux Black (1912 - 1990) was the eldest son of Cygnus Black I and Violetta Bulstrode. He married Irma Crabbe, and the couple had three children: Walburga, Alphard, and Cygnus Black II. Thus, he is a grandfather of Sirius and Regulus Black, as well as Bellatrix Lestrange, Andromeda Tonks, and Narcissa Malfoy.

Behind the scenes

 * Like many members of the Black family, the name Pollux comes from a star. It is the brightest star in the constellation Gemini. The name refers to Castor and Pollux, the twin sons of Zeus and Leda in Greek mythology. The name is traditionally thought to mean "much wine", since astrologers associate Pollux with prosperity and celebration with wine.
 * On the Black Family Tree, it states that Pollux was thirteen years old when he had his first child. This is most likely one of the numerous math mistakes made by J.K. Rowling (who frequently admits that math is not her strong suit).
 * Based on a statement by Horace Slughorn, Pollux may have been a member of the Slytherin House.