Atlacatl (Nahuatl Ātlācatl: ātl "water", tlācatl "human being" – whose death is sometimes put at 1528) is reputed to have been the name of the last ruler of an indigenous state based around the city of Cuzcatlan, in the southwestern periphery of Mesoamerica (present-day El Salvador), at the time of the Spanish conquest.

Atlacatl appears to have been a myth, however, as no contemporary chronicler mentions him.

Rather, much as in other Latin American countries, the romantic figure of the tragic Indian resistance leader is deployed in the nationalist discourse to lend grandeur and romance to the nation's formation in the "meeting of two worlds".

The myth remains powerful locally, however, and the name "Atlacatl" has been adopted by one of El Salvador's elite army battalions.