E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The evil genius of a house: a Nemesis. Cicero says: Who meditated killing himself that he might become the Alastor of Augustus, whom he hated. Shelley has a poem entitled Alastor, or The Spirit of Solitude. The word is Greek (alastr, the aveng ïng god, a title applied to Zeus); the Romans had their Jupiter Vindex; and we read in the Bible, Vengeance is mine. I will repay, saith the Lord (Rom. xii. 19).