The County Palatine of Durham was a jurisdiction in the North of England, within which the bishop of Durham had rights usually exclusive to the monarch. It developed from the Liberty of Durham, which emerged in the Anglo-Saxon period. The gradual acquisition of powers by the bishops led to Durham being recognised as a palatinate by the late thirteenth century, one of several such counties in England during the Middle Ages. The county palatine had its own government and institutions, which broadly mirrored those of the monarch and included several judicial courts. From the sixteenth century the palatine rights of the bishops were gradually reduced, and were finally abolished in 1836. The last palatine institution to survive was the court of chancery, which was abolished in 1972.

In England, Wales and Ireland a county palatine or palatinate was an area ruled by a hereditary nobleman enjoying special authority and autonomy from the rest of a kingdom. The name derives from the Latin adjective palātīnus, "relating to the palace", from the noun palātium, "palace". It thus implies the exercise of a quasi-royal prerogative within a county, that is to say, a jurisdiction ruled by an earl, the English equivalent of a count. A duchy palatine is similar but is ruled over by a duke, a nobleman of higher precedence than an earl or count.