Guillaume de Montmorency, Seigneur of Thoré (c. 1547-c. 1593) was a French noble, and military commander during the latter French Wars of Religion. Thoré was among those Catholic nobles who were perceived as soft on Protestantism, and as such during the Massacre of Saint Bartholomew he feared for his life. Shortly after the massacre as France descended back into civil war, Thoré, lacking military experience and keen to prove himself militarily joined the siege of La Rochelle.
Shortly after the siege and the end of the fourth war of religion. Thoré began to conspire against the crown. He was among those who led the ambitious Alençon's mind with the notion of rebelling in favour of the captive Navarre and Condé's liberty. When the conspiracy was uncovered, Thoré, whose involvement was known was ordered arrested. He and his brother Méru fled to Germany, seeking to raise an army. Successful in this endeavour they were held off from return by the captivity of their brother Montmorency who they feared would be executed if they re-entered France. At this time however fearful of Alençon's factionalism and desiring to be assured of his loyalty the king ordered Montmorency's release.
Thoré led an advanced party of German reiters into France in October 1575, his small force would however be annihilated by Guise at the Battle of Dormans. Despite this loss, the main mercenary force would enter France in early 1576, and in combination with Alençon's escape from court the crown would be pressured into the favourable Peace of Monsieur.