In heraldry, Saint George's Cross, the Cross of Saint George, is a red cross on a white background, which from the Late Middle Ages became associated with Saint George, the military saint, often depicted as a crusader.

Associated with the crusades, the red-on-white cross has its origins in the 10th century. It has been used as the ensign of the Republic of Genoa from perhaps as early as the 10th century.

The symbol was adopted by the Swabian League in the pre-Reformation Holy Roman Empire. George became associated as patron saint of England after the English reformation. Since then this flag is commonly identified as the national flag of England. Saint George is the patron saint of the Spanish semi-autonomous region of Catalonia and of the country of Georgia. It figures in the emblem (crest) of FC Barcelona, in Ecuadoran premier side Barcelona S.C. and as two quarters of the Flag of Barcelona. The national flag of Georgia (since 2004) supplements this cross with Jerusalem crosses.

Across the rest of Northern Italy as the symbol of Bologna, Padua, Reggio Emilia, Mantua, Vercelli, and Alessandria, the form has only received a cult of Saint George bolstering and simplification to the cross of Saint Ambrose, the origin of the cross in their civic designs, as the latter was adopted by the Commune of Milan in 1045, Ambrose having been a late 4th century bishop of that city.