Urbain Grandier (1590-1634) was a French catholic priest who was executed on charges of seduction and witchcraft in 1634.

Grandier served at the church of Sainte Croix in Loudun, a town in Vienne, France. He had something of a reputation as a ladies' man, and in 1632, a group of nuns from the local Ursuline convent accused him of having bewitched them, sending the demon Asmodai among others to commit evil and impudent acts with them. The accusations began with the testimony of a young novice, but soon grew — today, this is considered a case of collective hysteria. Grandier was arrested, interrogated and judged by an ecclesiastical tribunal. He was found innocent and the accusations were declared null.

Grandier, however, gained the enmity of Cardinal Richelieu after a public verbal attack against him. Richelieu ordered a new trial, with a "special" envoy, Jean de Laubardemont, a relative of the Mother Superior of the convent of Loudun. Grandier was arrested again at Angers, and the possibility of appealing to the Parlement of Paris was denied to him. Interrogated for a second time, the nuns (including the Mother Superior, Jeanne des Anges) did not renew their accusations, but the sentence had been passed before the second trial.

The judges (the clerics de Laubardemont, Lactance, Surin and Tranquille), after torturing the priest, presented fake documents signed by Grandier and several demons as a "proof" that he had made a diabolical pact. One of the acts was written in Latin and appeared to be signed by Grandier; another was almost illegible, had many strange symbols, and was "signed" by several demons with their seals, and by Satan himself clearly written "Satanas". It is unknown if Grandier wrote the acts under torture or if they were a falsification; more, it is unknown whether Grandier's signature was his or forged.

Richelieu consummated his vengeance. In 1634, Grandier was found guilty of diabolical pact and the practice of witchcraft, sentenced to death, tortured, and then burnt alive at the stake.