In Greek mythology, Alastor was the personification of blood feuds between clashing families. He was an avenging spirit/deity, a spirit of vengeance, considered the male counterpart to Nemesis. In Christian demonology, Alastor was the chief executioner in Hell and was considered very cruel. Alastor in Greek means "unforgettable", though "avenger" is considered an adequate interpretation. Alastor, also called The Spirit of Solitude is also the name of a poem by Percy Bysshe Shelley in 1816.