Conquistador is a Spanish term meaning conqueror. It is typically used to refer to the explorers, adventurers, and soldiers that conquered and claimed most of the Americas for Spain, especially in the 1500s.
The conquistadors had significant advantages over the natives. They brought with them armies, firearms, and other materials otherwise unknown to the natives. In addition to introducing new animals to the New World, the conquistadors unfortunately brought diseases that wiped out entire native populations.
Some notable conquistadors include: Hernán Cortés, who conquered the Aztec Empire, claiming México and Honduras for Spain; Francisco Pizarro, who led the conquest of the Incan Empire in Peru; and Juan Ponce de León, who took over Puerto Rico and present-day Florida.