Eleoncio Mercedes (September 12, 1957 – December 22, 1985) was a Dominican boxer, who was world champion in the Flyweight division.

[1] Born in La Romana, Mercedes campaigned most of his career in the western United States and in Mexico.

He suffered his first defeat when he lost by a decision in Las Vegas to future world champion Joey Olivo, in Mercedes' third bout as a paid fighter.

He lost to Candido Tellez but also beat former world champion Guty Espadas, by a knockout in nine during that span.

Mercedes caused another surprise among many boxing fans by defeating Castillo by a decision in 15 rounds and becoming WBC and Lineal Flyweight champion.