Elladora Nott (née Black) (1850 – 1931) was a pure-blood witch and a member of the House of Black. She married Samuel Nott, and had three children with him. She was the grandmother of James Potter, and as such, the great-grandmother of Harry Potter.
Born as the youngest daughter of Cygnus Black I and Ella Black, Elladora was best known for instituting the policy of cutting off the heads of the family house-elves and mounting them on the wall once they became too old to carry a tea tray, and this was apparently still a tradition by the time of her great-grandchildren. Her siblings were Sirius Black I, Phineas Nigellus, and Iola.
She married Samuel Nott, and gave birth to Euphemia Nott (later Potter), Demetrius Nott and Cantankerus Nott. It is possible that she was also a Marchioness of Averdale because of her marriage to Samuel Nott.
Dominus Mundi (mentioned only)