Girart de Roussillon, also called Girard, Gérard II, Gyrart de Vienne, and Girart de Fraite, (c. 810–877/879?) was a Burgundian chief who became Count of Paris in 837, and embraced the cause of Lothair I against Charles the Bald. He was a son of Leuthard I, Count of Fézensac and of Paris, and his wife Grimildis.
Girart is not described as being from Roussillon in authentic historical sources. The placename in his title is derived from a castle he built on Mont Lassois, near Vix and Châtillon-sur-Seine (Côte-d'Or).
Girart de Roussillon also is an epic figure in the cycle of Carolingian romances, collectively known as the Matter of France. In the genealogy of the cycle’s legendary heroes, Girart is a son of Doon de Mayence and appears in the various irreconcilable events.