Admiral Sir Nigel Essenhigh, RN, is a British admiral who served as First Sea Lord of the Royal Navy from 2001-2002.

Essenhigh was born in Newcastle. He joined the Royal Navy in 1963 and qualified as a Principal Warfare Officer in 1972, specialising in navigation.

After his appointment to Commander in 1980 he joined the Ministry of Defence for duty with Naval Manpower Training and took command of the Type 42 destroyer HMS Nottingham in 1982. His next post was on board HMS Ark Royal during its construction in 1984 and he was promoted to Captain in 1985.

After graduating from the Royal College of Defence Studies in 1987 he returned to the MOD and the Naval Plans Department, and he took command of another destroyer, HMS Exeter, from 1989 to 1992.

Promotion to Rear Admiral came in 1994 when he took up the position of Hydrographer to the Royal Navy and he became Assistant Chief of Defence Staff (Programmes) in 1996. In 1998 he was promoted to full Admiral and was appointed to the job of Commander In Chief Fleet.