Cornelia Delamere Pendergast, often called "Great-Aunt Cornelia" was Aloysius Pendergast's great-aunt. She was the only daughter among Boethius Pendergast's three children. Like most of the Louisiana branch of the Pendergast family, Cornelia lived in the Maison de la Rochenoire in New Orleans. After an angry mob burned Rochenoire to the ground, Cornelia's husband moved their family permanently to their estate of Ravenscry in Dutchess County, New York. Having inherited the Pendergast family's tendency to madness, she later poisoned her husband and two children, along with her father, mother and her brother Ambergris, believing them all to be possessed. She was subsequently confined to Mount Mercy Hospital for the Criminally Insane.