Pollux Cygnus Black (1912-1990) was the eldest of Cygnus Black II's four children, who married Irma Crabbe and fathered three children:
- Walburga (1929) married Orion Black and had two sons.
- Alphard (1930-1977)
- Cygnus (1931) married Druella Rosier and had three daughters.
Pollux appears as a handsome stern looking man with a love for bow ties and a dark moustache. He enjoys dressing up.
Pollux was born in 1912 to Cygnus and Violetta Black and had three younger siblings: Cassiopeia (1915), Marius (1918) and Dorea (1920). He went to Hogwarts from 1923 to 1930 and was sorted into Slytherin House.
He met and married Irma Crabbe at some point between 1930 and 1935. The two had a strong opinion on Blood Traitors and Muggleborns that would be passed on to their three children, five grandchildren en eventually three great-grandchildren and two great-great-grandchildren.