The Spanish conquest of the Aztec Empire, also known as the Conquest of Mexico, was one of the primary events in the Spanish colonization of the Americas. There are multiple 16th-century narratives of the events by Spanish conquistadors, their indigenous allies, and the defeated Aztecs. It was not solely a contest between a small contingent of Spaniards defeating the Aztec Empire but rather the creation of a coalition of Spanish invaders with tributaries to the Aztecs, and most especially the Aztecs' indigenous enemies and rivals. They combined forces to defeat the Mexica of Tenochtitlan over a two-year period. For the Spanish, the expedition to Mexico was part of a project of Spanish colonization of the New World after twenty-five years of permanent Spanish settlement and further exploration in the Caribbean.

The capture of Tenochtitlan marked the beginning of a 300-year colonial period, during which Mexico was known as "New Spain" ruled by a viceroy in the name of the Spanish monarch. Colonial Mexico had key elements to attract Spanish immigrants: (1) dense and politically complex indigenous populations (especially in the central part) that could be compelled to work, and (2) huge mineral wealth, especially major silver deposits in the northern regions Zacatecas and Guanajuato. The Viceroyalty of Peru also had those two important elements, so that New Spain and Peru were the seats of Spanish power and the source of its wealth, until other viceroyalties were created in Spanish South America in the late 18th century. This wealth made Spain the dominant power in Europe, rivalling England, France, and (after its independence from Spain) the Netherlands.