Who was the Aztec emperor when the conquistadors showed up?

The Aztec emperor when the conquistadors, led by Hernán Cortés, arrived in 1519 was Moctezuma II. He ruled from 1502 until his death in 1520 and was known for his extensive empire and the wealth of the Aztec civilization. Moctezuma initially welcomed Cortés, believing he might be a deity, but this ultimately led to conflict and the downfall of the Aztec Empire.