Although best known as a folktale, the character of Bluebeard appears to derive from legends related to historical individuals in Brittany. One source is believed to have been the 15th-century Breton nobleman and later confessed serial killer Gilles de Rais. However, Gilles de Rais did not kill his wife, nor were any bodies found on his property, and the crimes for which he was convicted involved the sexually-driven, brutal murder of children and not a punishment for perceived betrayal.
Another possible source stems from the story of the early Breton king Conomor the Accursed and his wife Tryphine. This is recorded in a biography of St. Gildas, written five centuries after his death in the sixth century. It describes how after Conomor married Tryphine, she was warned by the ghosts of his previous wives that he murders them when they become pregnant. Pregnant, she flees; he catches and beheads her, but St. Gildas miraculously restores her to life, and when he brings her to Conomor, the walls of his castle crumble and kill him. Conomor is a historical figure, known locally as a werewolf, and various local churches are dedicated to Saint Tryphine and her son, Saint Tremeur.
The character's blue beard is regarded as a symbol of his otherworldly origins.