Geoffrey de Mandeville II, 1st Earl of Essex (died September 1144) was a prominent figure during the reign of King Stephen of England.
She confirmed his custody of the Tower, forgave the large debts his father had incurred to the crown, granted him the Norman lands of Eudo le Dapifer, and appointed him Sheriff of Essex and Hertfordshire, Middlesex and London.
The king arrested the earl in 1143 and, threatened with execution, Geoffrey surrendered his castles of Pleshey and Saffron Walden as well as custody of the Tower of London to Stephen.
He was besieged by King Stephen and met his death attacking Burwell Castle in September 1144 in consequence of an arrow wound received in a skirmish.
Many coffins were smashed and bones thrown on the floor, and the skull of Geoffrey de Mandeville was stolen, placing suspicion for the theft on a private collector.
His career as an outlaw exemplifies the worst excesses of the civil wars of 1140–1147, and it is possible that the deeds of Mandeville inspired the rhetorical description of this period in the Peterborough Chronicle, when "men said openly that Christ and his saints were asleep".
An account of Geoffrey's outlaw actions and the taking of Ramsey Abbey provides for elements of the backstory for two of Ellis Peters' "Brother Cadfael" books, The Potter's Field and The Holy Thief.