justiciar or chief minister of England (1180–89) under King Henry II who was the reputed author of the first authoritative text on the common law, Tractatus de legibus et consuetudinibus regni Angliae (c. 1188; “Treatise on the Laws and Customs of the Kingdom of England”). This work greatly extended the scope of the common law at the expense of canon law and local law, and in English legal history the period is known as the Age of Glanville. The actual author of the Tractatus, however, may have been either of two later justiciars: Hubert Walter (also archbishop of Canterbury and Glanville's nephew) or Geoffrey Fitzpeter.

As justiciar, Glanville was, in effect, viceroy of England while Henry II was fighting in France. During his tenure a permanent royal court (Curia Regis) began to sit at Westminster, and the inquest (a forerunner of the jury trial) came to be widely used in cases involving land. Removed from office by Henry's son and successor, Richard I, Glanville subsequently accompanied Richard on the Third Crusade.