Fernando Alejandre Martínez is Spanish Army officer. A General of the Army, he served as the 10th Chief of the Defence Staff of Spain from 24 March 2017 to 15 January 2020, when was ceased and succeeded by Miguel Ángel Villarroya Vilalta.

The Chief of the Defence Staff is the highest-ranking military officer in the Spanish Armed Forces and is the principal military advisor to the Prime Minister, the Minister of Defence, the National Defence Council and the National Security Council. It is the fourth military authority of the country after the Monarch, the Prime Minister and the Minister of Defence because the Secretary of State for Defence and the Under-Secretary of Defence do not have military authority.