Fernando Macarro Castillo (20 January 1920 in Alconada – 24 November 2016 in Madrid), better known by his pseudonym Marcos Ana, was a Spanish poet and is considered by numerous sources Spain's longest serving political prisoner. Under the Francoist Spain, he was convicted of first degree murder of three people (a priest, a postman and a farmer) at the age of 19 in 1939, crimes he always denied having committed. He spent 23 years in prison, longer than any other republican combatant, being released in 1961 and exiled in Paris. He told his story in his 2007 publication Ditemi com'è un albero.