Regulus Arcturus Black was a pure-blood wizard, the younger son of Orion and Walburga Black, and the brother of Sirius Black. A member of the noble House of Black, Regulus was sorted into Slytherin House at Hogwarts and served as the Seeker for the Slytherin Quidditch team. Initially a loyal follower of Lord Voldemort and a Death Eater, Regulus became disillusioned with the Dark Lord. In an extraordinary act of bravery and defiance, he uncovered Voldemort's secret of the Horcruxes and sacrificed his own life in an attempt to destroy one of them, Slytherin's Locket. His story is a key element in understanding the fight against Voldemort and is revealed posthumously, primarily through the testimony of his loyal house-elf, Kreacher.
Born in 1961, Regulus grew up at Number Twelve, Grimmauld Place. Unlike his rebellious older brother, Sirius, Regulus embraced his family's pure-blood supremacist ideology. He was favored by his parents, who saw him as a dutiful son who would uphold the family's dark legacy. His bedroom was decorated with Slytherin banners, the Black family crest, and newspaper clippings about Lord Voldemort and his Death Eaters, indicating an early fascination with the Dark Arts and Voldemort's cause.
Regulus attended Hogwarts School of Witchcraft and Wizardry from approximately 1972 to 1979, where he was sorted into Slytherin House. He was a member of the Slug Club, a testament to his ambition and talent, as Horace Slughorn only collected students he believed were destined for success. He was also a skilled Quidditch player, serving as the Seeker for his house team. A photograph of the 1976 Slytherin Quidditch team with Regulus at its center was still in his bedroom years after his death.
At around the age of sixteen, Regulus fulfilled his family's expectations by joining the Death Eaters. Sirius Black believed his brother was drawn in by the grandeur and power promised by Voldemort. However, Regulus soon grew to fear the Dark Lord and began to have second thoughts about his allegiance. The turning point came when Voldemort, requiring a house-elf to test the defenses guarding his Horcrux, chose Kreacher. Voldemort took Kreacher to a hidden sea cave, forced him to drink the Emerald Potion in the basin, and left him to die at the hands of the Inferi in the surrounding lake. Voldemort underestimated house-elf magic, and Kreacher was able to Disapparate back to his master, Regulus.
Horrified by what Voldemort had done to Kreacher, and realizing that the locket hidden in the cave was a Horcrux, Regulus resolved to act. He created a perfect replica of Slytherin's Locket and placed a note inside it, addressed to the Dark Lord. In 1979, he ordered Kreacher to take him to the sea cave. There, Regulus drank the debilitating potion himself to access the basin. He then ordered Kreacher to swap the lockets, take the real one, and escape with the command to destroy it and to never reveal the truth to the Black family. Weakened and driven mad with thirst by the potion, Regulus crawled to the edge of the water and was dragged to his death by the Inferi. He was only eighteen years old. His family believed he had been killed by Voldemort's enemies, never knowing of his ultimate betrayal of the Dark Lord.
Regulus was described as being thinner, younger, and “less conventionally handsome” than his brother, Sirius Black, though he possessed the same dark hair and a “certain haughty look.” Initially, he was ambitious and proud, eager to please his parents and live up to the Black family name. Sirius remembered him as a “soft-hearted idiot” who was “drawn to the glamour of the Dark Arts.” However, his final actions reveal a character of immense courage, cunning, and moral depth. His affection and kind treatment of Kreacher set him apart from many pure-bloods, and this loyalty was ultimately the catalyst for his redemption. His sacrifice demonstrates a profound bravery that rivaled that of any Gryffindor.