Answer:
Hernán Cortés.
Step-by-step explanation:
He was a Spanish conquistador who led an expedition that caused the fall of the Aztec empire and brought large portions of what now is mainland Mexico under the rule of the King of Castile.
In order to do that with a small group of Spanish conquistadors, Cortés allied with city-states opposed to the Aztecs. After defeating them the Spanish founded Mexico City on the ruins of Tenochtitlan.
I hope this answer helps you.