Prospero Fagnani (born in Italy, place and date of birth uncertain; died 1678) was an Italian canon lawyer.
Pope Benedict XIV gave this work the highest praise, and its authority is still continually appealed to in the Roman Congregations.
The first edition was published at Rome, in 1661, under the title of "Jus canonicum seu commentaria absolutissima in quinque libros Decretalium".
Fagnani is reproached with excessive rigour in his commentary on the chapter of the Decretals "Ne innitaris" (Book I, De constitutionibus), in which he combats the doctrine of probabilism.
Saint Alphonsus calls him "magnus rigoristarum princeps", the great prince of the rigorists (Homo apostolicus, Tract.