The barbarian kingdoms, also known as the post-Roman kingdoms, the western kingdoms, or the early medieval kingdoms, were the states founded by various non-Roman, primarily Germanic, peoples in Western Europe and North Africa following the collapse of the Western Roman Empire in the fifth century. The formation of the barbarian kingdoms was a complicated, gradual and largely unintentional process, as the Roman state failed to handle barbarian migrants on the imperial borders, leading to both invasions and invitations into imperial territory, but simultaneously denied barbarians the ability to properly integrate into the imperial framework. The influence of barbarian rulers, at first local warlords and client kings without firm connections to any territories, increased as Roman emperors and usurpers used them as pawns in civil wars. It was only after the collapse of effective Western Roman central authority that the barbarian realms transitioned into proper territorial kingdoms.

The term Western Roman Empire is used in modern historiography to refer to the western provinces of the Roman Empire, collectively, during any period in which they were administered separately from the eastern provinces by a separate, independent imperial court. Particularly during the period from AD 395 to 476, there were separate, coequal courts dividing the governance of the empire into the Western provinces and the Eastern provinces with a distinct imperial succession in the separate courts. The terms Western Roman Empire and Eastern Roman Empire were coined in modern times to describe political entities that were de facto independent; contemporary Romans did not consider the Empire to have been split into two empires but viewed it as a single polity governed by two imperial courts for administrative expediency. The Western Empire collapsed in 476, and the Western imperial court in Ravenna disappeared by AD 554, at the end of Justinian's Gothic War.