a French-Italian painter, draughtsman and etcher. He was mainly active in Rome as a history and staffage painter and enjoyed high-level patronage. He was the brother of the painters Jacques Courtois (Giacomo Cortese) and Jean-François Courtois. Guillaume Courtois was mainly a history painter of Christian religious and mythological scenes. He was also in demand as a staffage painter. He is sometimes referred to as a battle painter because of his involvement in the decorative project in the chapel of the Congregation of the Jesuits, a small oratory housed in a room of the Collegio Romano adjacent to the Sant'Ignazio Church, Rome.
