The Varenne is a river of Normandy, France, 39 kilometres (24 mi) in length, flowing through the department of Seine-Maritime. It is a tributary of the river Arques. The river is the ultimate source of the surname and given name Warren, via William de Warenne of Bellencombre castle, his hereditary seat. de Warenne was a companion of William the Conqueror and made first Earl of Surrey in 1088 as reward for his service during the Norman Conquest.