Fernando Rielo was born on 28 August 1923 in Madrid to Enrique Rielo and his wife, Pilar Pardal. He was keenly interested in drawing during his childhood years. When he was an adolescent, the Spanish Civil War broke out.
Rielo once stood before a firing squad during the war, on the day of his First Holy Communion. The leader of the squad asked him to renounce his faith, but Rielo refused. However, the leader finally decided not to order his men to shoot Rielo.