Bernard Gui was an inquisitor of the Dominican Order in the late Middle Ages during the Medieval Inquisition. He is known for his tenure in Toulouse at the behest of Pope Clement V between 1307 and 1324.

Working in the area of Toulouse (in modern France), he executed 42 people out of over 700 guilty verdicts in fifteen years of office. He produced a famous work, Practica Inquisitionis Heretice Pravitatis (The Conduct of the Inquisition of Heretical Depravity), which detailed a list of serious heresies in the early 14th century, and how inquisitors should conduct themselves in the questioning of members of particular groups. The groups he concentrated on were the Cathars, Waldenses, false Apostles, Beguins, Jews, as well as sorcerers and necromancers.

Legacy

Bernard Gui was a character in the historical fiction book The Name of the Rose by Umberto Eco.