Alejandro Muñoz Moreno (April 24, 1922 – December 16, 2000), better known as Blue Demon (Demonio Azul in Spanish), was a Mexican luchador Enmascarado (Masked professional wrestler) who was widely considered to be one of the greatest Mexican wrestlers of his time. He was affectionately referred to as "Blue" and was known for his signature blue wrestling mask.

Alejandro Muñoz Moreno was born April 24, 1922 in Rinconada, Nuevo León Mexico. He was the child of farmers and was the fifth of twelve children. At a young age, Alejandro dropped out of school and moved to Monterrey, where his uncle gave him a job working on the National Railroad. His co-workers there gave him the nickname 'Manotas', referring to his large, powerful hands.

A chance meeting with the famous Mexican wrestler Rolando Vera piqued his interest in Lucha Libre, Vera even offering to tutor him and help him start a career. He began wrestling without a mask in Laredo, Texas. His first match was against Chema Lopez on March 12, 1948, which he won handily. Adopting the mask and persona of The Blue Demon, he headed back to Mexico to start a real career. His first appearance as The Blue Demon was in Mexico City in September 1948, where he fought Benny Arcilla. Blue began his career in the ring as a rudo (a bad guy). From there, he formed a famous tag-team with another well-known masked luchador named The Black Shadow, and the two became known as Los Hermanos Shadow (The Shadow Brothers).