Francesco Maria Guazzo, aka Guaccio, aka Guaccius (15??-16??) was an Italian priest in Milan. He wrote a book, the Compendium Maleficarum (Compendium of the Witches), in which he cited numerous experts on the subject, among them Nicholas Remy.

He described the eleven formulae or ceremonies previous to the vow to Satan, allegedly necessary to participate of the Sabbath; besides, Guazzo offered detailed descriptions of the sexual relationships between men and succubi, and women and incubi.

Guazzo established also a classification of the demons, inspired by a previous work by Michael Psellus.

See also Guazzo's classification of demons