Siger of Brabant (Sigerus, Sighier, Sigieri or Sygerius de Brabantia; c. 1240 – before 10 November 1284) was a 13th-century philosopher from the southern Low Countries who was an important proponent of Averroism.
In 1266, he was attached to the Faculty of Arts in the University of Paris at the time when a riot erupted between the French and Picard "nations" of students—a series of loosely organized fraternities.
A 13th-century sonnet by one Durante (xcii.9–14) says that he was executed at Orvieto: "a ghiado il fe' morire a gran dolore, Nella corte di Roma ad Orbivieto."
In December 1270, Averroism was condemned by ecclesiastical authority, and during his whole life Siger was exposed to persecution both from the Church and from purely philosophic opponents.
In Dante Alighieri's The Divine Comedy, Siger of Brabant is found in the Fourth Sphere of Paradise for being a positive example of Prudence, Justice, Temperance, and Fortitude.