Druella Rosier

Druella Rosier is a pure-blood witch who married Cygnus Black III. The couple had three daughters: Bellatrix, Andromeda, and Narcissa Black. Through Bellatrix, she is the mother-in-law of Death Eater Rodolphus Lestrange. Through Andromeda, who was disowned for marrying Muggle-born wizard Ted Tonks, Druella is the grandmother of Nymphadora Tonks and great-grandmother of Teddy Lupin. Through Narcissa, she is the mother-in-law of Lucius Malfoy, the grandmother of Draco Malfoy and great-grandmother of Scorpius Malfoy. Druella may be related to Evan Rosier, a Death Eater killed by Alastor Moody during the First Wizarding War.

Behind the scenes

 * Based on a statement by Horace Slughorn, Druella may have been a member of the Slytherin House, like her husband Cygnus.
 * In the Black family name Ella also appeares before Druella married Cygnus. There were Ella Max and her daughter Elladora.

Etymology
Druella may be a combination of the names Drusilla, often shorted to Dru and meaning "dewy-eyed" or "fruitful", and Ella, a Norman name derived from the Germanic word ali, meaning "other". Drusilla was the name of infamous Roman Emperor Caligula's favourite sister, as well as the daughter named after her.

Notes and references
Druella Rosier