Daimyo, in Japanese history, a landholding feudal lord. From the 15th century to the late 19th, Japan was divided into feudal realms ruled by daimyo. In theory, the daimyo were vassals of the shogun (military governor), but their power was often so great that their domains could be considered virtually independent. Daimyo were of the samurai class; they ruled from strong castles and led private armies of thousands of samurai and peasant troops. They derived their wealth from taxes collected from peasants and merchants in their domains.

Daimyo arose in the 15th century when the shogunate was weak, and they flourished for more than a century. They lost much of their power after 1603, when Tokugawa Ieyasu established the Tokugawa dynasty of shoguns and a strong central government. After the fall of the shogunate in 1868, the daimyo lost their domains; in 1871 they were given pensions and the status of non-landholding nobility.