Claude de Mesmes, comte d'Avaux (1595–1650) was a 17th-century French diplomat and public administrator. He was sent in various missions to Venice, Rome, Germany, Sweden, Denmark, and Poland by Richelieu. In 1635 he guided the negotiations of the Treaty of Stuhmsdorf, which extended the truce between Poland and Sweden. These two countries had fought each other in the Polish-Swedish war of 1626–1629, which ended in a truce rather than a piece. France wanted peace between Poland and Sweden because the Swedes were fighting for France in Germany and the Poles would have menaced their flank.