Louis III de La Trémoille (1521 – 25 March 1577), 1st Duke of Thouars, was a sixteenth-century French nobleman of the La Tremoille family. He was the son of François II de La Trémoille and his wife, Anne de Laval. Louis accompanied the dauphin on a voyage to Perpignan in 1542, served in the war against the English in Picardy and was one of the four barons given as a hostage of the Holy Ampoule at the consecration of Henry II, and one of the hostages of the peace treaty concluded in 1542 between France and England.