Montezuma II was the ninth emperor of the Aztec Empire, ruling from 1502 until his death in 1520, and is best known for his encounter with Spanish conquistador Hernán Cortés, which led to the fall of the Aztec Empire. His reign was marked by extensive military campaigns and the expansion of the empire, but his legacy is largely defined by the catastrophic impact of European colonization and the subsequent collapse of Aztec civilization.