Answer:
Hernando Cortés.
Step-by-step explanation:
Basically, everybody was running around screaming that Cortés was the god that was thought to come during that year, and at first the Aztecs did too - even sent Cortés some valuables and stuff. Then, though, the Aztecs were like... yeah, but hold on, this guy is described to look like a human and all, so maybe not...
Yeah, Cortés didn't like that too much. He marched on over there (after burning down his ships so those that were nervous about facing the Aztecs couldn't leave and were forced to follow him) and him and his army started smacking (er.. battling, i guess) the Aztec Empire.
The Spaniards had guns; the Aztecs did not. Also, the Spanish brought some ugly smallpox germs along with them, and the Aztecs weren't used to those infections and had no immunity, so they either died or got all weak and sick.
So yeah, then the Aztec Empire went down, the Spanish built a cathedral or church or something like that, and the rest is history... (Well, I guess it was all history from the beginning, just intentionally poorly-narrated on my part.)
There ya have it - Hernando Cortés gets bragging rights in history for bringing down the Aztecs.