Regulus Black I

Regulus Black (1906 - 1959) was the youngest child of Sirius Black and Hesper Gamp. Regulus never married, and never had children.

Behind the scenes

 * Based on a statement by Horace Slughorn, Regulus may have been a member of the Slytherin House.

Etymology
Regulus is a name of a star. It means a "little king". In the House of Black was also one more member called Regulus. Regulus I was a a greatuncle of Regulus II.

Notes and references
On the Black family tree in the film, Regulus I is decipted more like a woman than man.