Tlahtoāni[1] (Classical Nahuatl: tlahtoāni pronounced [t͡ɬaʔtoˈaːniˀ] ⓘ, "ruler, sovereign"; plural tlahtohqueh[2] [t͡ɬaʔˈtoʔkeʔ]) is a historical title used by the dynastic rulers of āltepēmeh (singular āltepētl, often translated into English as "city-state"), autonomous political entities formed by many pre-Columbian Nahuatl-speaking peoples in the Valley of Mexico during the Postclassic Period.

The tlahtoāni wielded ultimate authority over all land within the āltepētl, overseeing tribute collection, market activities, temple affairs, and the resolution of judicial disputes.

[4] Typically a dynastic ruler hailing from the royal lineage, the tlahtoāni served for life.

[4] During times of war, the tlahtoāni would be in charge of creating battle plans, and making strategies for his army.

He would draft these plans after receiving information from various scouts, messengers, and spies who were sent out to an enemy āltepētl (city-state).