Francisco Javier Castaños Aragorri, 1st Duke of Bailén (1758–1852) was a Spanish military commander during the French Revolutionary Wars and the Napoleonic Wars. He presided over the Regency Council of Spain and the Indies, in 1810. From July to September 1834, he served as the first president of the Senate of Spain, at that time called the House of Peers.

Captain General has been the highest rank in the Spanish Army since the 18th century. A five-star rank with NATO code OF-10, it is equivalent to a field marshal of the armies of numerous countries, a general of the Army of the United States, a captain general of the Spanish Navy (Armada Española) or a Captain general of the Air Force in the Spanish Air and Space Force (Ejército del Aire y del Espacio). A Captain General's insignia consists of two command sticks under five four-pointed stars below the Royal Crown.