The Crown of Aragon (Aragonese: Corona d'Aragón, Catalan: Corona d'Aragó, Latin: Corona Aragonum, Spanish: Corona de Aragón) was a personal and dynastic union of multiple titles and states in the hands of the King of Aragon. At the height of its power in the 14th and 15th centuries, the Crown of Aragon was a thalassocracy (a state with primarily maritime realms) controlling a large portion of the present-day eastern Spain and southwestern France, as well as some of the major islands and mainland possessions stretching across the Mediterranean as far as Greece. The component realms of the Crown were not united politically except at the level of the king, who ruled over each autonomous polity according to its own laws, raising funds under each tax structure, dealing separately with each cortes. Put in contemporary terms, the disparate lands of Aragon functioned more as a confederacy of cultures rather than as a single country. In this sense, the larger Crown of Aragon must not be confused with one of its constituent parts, the Kingdom of Aragon, from which it takes its name.

Aragon ( /ˈærəɡɒn/ or /ˈærəɡən/), also known in Spanish and Aragonese as Aragón ([aɾaˈɣon]) and in Catalan as Aragó ([əɾəˈɣo] or [aɾaˈɣo]), is a modern autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. Located in northeastern Spain, the Aragonese autonomous community comprises three provinces (from north to south): Huesca, Zaragoza, and Teruel. Its capital is Zaragoza (also called Saragossa in English). The current Statute of Autonomy declares Aragon a nationality of Spain.

Aragon's northern province of Huesca borders France and is positioned in the middle of the Pyrenees. Within Spain, the community is flanked by Catalonia on the east, Valencia and Castile–La Mancha to the south, and Castile and León, La Rioja, and Navarre to the west.

Covering an area of 47,719 km² (18,424 sq mi), the region's terrain ranges diversely from permanent glaciers to verdant valleys, rich pasture lands and orchards, through to the arid steppe plains of the central lowlands. Aragon is home to many rivers—most notably, the river Ebro, Spain's largest river in volume, which runs west-east across the entire region through the province of Zaragoza. It is also home to the Aneto, the highest mountain in the Pyrenees.