He married Melania Macmillan, who bore him a daughter, Lucretia, and a son, Orion. Arcturus became a grandfather after Orion married their cousin Walburga and had two sons, Sirius and Regulus. Lucretia had no children from her marriage to Ignatius Prewett.
At some point, Arcturus was awarded the Order of Merlin, First Class, for "Services to the Ministry". His grandson Sirius believed that he received the honour because he had given the Ministry a large amount of gold. The medal was left at 12 Grimmauld Place after his death; in 1995, Sirius found the medal while cleaning and threw it into a rubbish sack with contempt.
Arcturus died in 1991. He had outlived both his siblings, his son, his daughter-in-law, and his younger grandson. He was survived by his daughter and his elder grandson.
- Based on a statement by Horace Slughorn, Arcturus may have been a member of the Slytherin House. However, he attended Hogwarts c. 1912-1919, and Slughorn did not become the Potions master until approximately 1931.
- Arcturus' second grandson was named Regulus Arcturus Black. Regulus was probably named in honour of his grandfather and his great-uncle, Arcturus's brother.
- On the Black family tree shown on the film adaptation of Harry Potter and the Order of the Phoenix, Arcturus's name is misspelt as "Arctorus".
- Although the Macmillan family would now be considered blood traitors, his marriage to Melania in his family's eyes was apparently a "respectable" pure-blood marriage, as he wasn't disowned.
Arcturus is the name of the brightest star in the constellation Boötes. Its name derives from Ancient Greek Αρκτοῦρος, meaning "bear guard"; this refers to the story in Greek mythology that Zeus placed Arcturus in the sky to look after Arcas and Callisto, who were turned into bears and then into the constellations Ursa Major and Ursa Minor to protect them from Hera's wrath.
- Harry Potter and the Order of the Phoenix (Indirectly mentioned only)
- Harry Potter and the Order of the Phoenix (film) (Appears on Black family tapestry)
- Harry Potter and the Order of the Phoenix (video game) (Seen on Black family tree tapestry)
- Harry Potter and the Deathly Hallows: Part 1 (video game) (Seen on Black family tree tapestry)
- Pottermore (Mentioned only)
- Wizarding World (Mentioned only)