Auxilius of Naples (which has been considered a pseudonym) was an ecclesiastical writer. To him are attributed a series of writings that deal with the controversies concerning the succession and fate of Pope Formosus (891-896), and especially the validity of the orders conferred by him. Auxilius was a Frank, who was ordained a priest, or perhaps only a deacon, in Rome by Formosus, and lived later in southern Italy, apparently at Naples.