ancient British tribe that inhabited the region that became Essex. In the mid-50s BC their prince, Mandubracius, was driven into exile by Cassivellaunus, king of the aggressive Catuvellauni. Caesar (Caesar, Julius)'s second invasion of Britain was going poorly in 54 BC, when the Trinovantes joined him and induced other tribes to fight with him against Cassivellaunus. Caesar captured the capital of the Catuvellauni; although he withdrew to Gaul, the Trinovantes were protected and Mandubracius restored under the terms of the treaty. It is not clear how long they maintained their independence. They were ruled by the Catuvellauni during the reign of Cunobelinus (c. AD 5–c. 40) and were liberated during the Roman invasion of AD 43 under the emperor Claudius.

The tribe's enthusiasm for Roman rule was short-lived. In 49 the first Roman colony was founded at Camulodunum (now Colchester) on land taken from them. To the Trinovantes the behaviour of the Roman colonists was as oppressive as the rule of the Catuvellauni. In 60 they joined the revolt of Boudicca (Boadicea), queen of the Iceni, and sacked Camulodunum. The revolt was suppressed in 61, and Camulodunum was rebuilt. But the town never recovered its economic and political importance, although it remained the centre of Roman religion in Britain. The Trinovantes do not reappear in history. The region's farms, timber, and pottery industries ensured its importance in Roman times. In medieval literature the Trinovantes are associated with the arrival in Britain of the legendary Trojans Brutus and Corineus, who gave their names to Britain and Cornwall, respectively.