Vice-Admiral Sir William Berkeley (1639 – 1 June 1666) was a Royal Navy officer who saw service during the Second Anglo-Dutch War, rising to the rank of vice-admiral.
Berkeley was born into a noble family, one of the younger sons of a courtier of King Charles II, and a younger brother of one of the King´s favourites. He joined the Royal Navy and enjoyed a meteoric rise owing to these important sources of patronage, something he himself acknowledged. After service in the Mediterranean, and time spent commanding his own ships, he was advanced to flag rank and joined the Royal fleets assembling for battle during the Second Anglo-Dutch War. He was a junior flag officer at the Battle of Lowestoft in 1665, during which his brother was killed. Caustic comments were made about his conduct, including by the poet and satirist Andrew Marvell.