Guy III of Châtillon, Count of Saint-Pol (died 1289) was a French nobleman, and was a younger son of Hugh I, Count of Blois, and Mary, Countess of Blois.

[1] While his elder brother John I of Châtillon succeeded to their mother's County of Blois, Guy was given their father's county of Saint-Pol-sur-Ternoise at his death in 1248.

On January 16, 1255, he married Matilda of Brabant, Countess of Artois,[2] daughter of Henry II, Duke of Brabant and Marie of Hohenstaufen, and thereafter was a supporter of his brother-in-law Henry III against Guelders.

They had: He joined the Eighth Crusade (1270) and the ill-fated Crusade of Aragón of Philip III of France.