Atlácatl (Nahuatl Ātlācatl: ātl "water", tlācatl "human being"; died c. 1528) is reputed to have been the name of the last ruler of an Indigenous state based around the city of Cuzcatlan, in the southeastern periphery of Mesoamerica (present-day El Salvador), at the time of the Spanish conquest.

With a standing army and lucrative cacao and Indigo exports, this wealthy state had resisted several Mayan Calakmul ally invasions and was one of the strongest in the region.

It was later developed as a nation-building myth in modern Salvadoran nationalist discourse, symbolising Cuzcatlan's courageous resistance against the invading Spanish forces.

Alvarado's own account records that when he entered the city of Cuzcatlan he found it partly abandoned, the men all having fled to the mountainous region nearby.

Finally, in 1528, Diego de Alvarado and his Indian auxiliaries set out on another attack on Cuzcatlan, during the defense of which the Nawat Pipil forces were defeated.