The House of Angelos, Latinised as Angelus, was a Byzantine Greek noble family that produced several Emperors and other prominent nobles during the middle and late Byzantine Empire. The family rose to prominence through the marriage of its founder, Constantine Angelos, with Theodora Komnene, the youngest daughter of Emperor Alexios I Komnenos. As imperial relatives, the Angeloi held various high titles and military commands under Emperor Manuel I Komnenos. In 1185, following a revolt against Andronikos I Komnenos, Isaac II Angelos rose to the throne establishing the Angeloi as the new imperial family that ruled until 1204. The period was marked by the decline and fragmentation of the Byzantine Empire, culminating in its dissolution by the Fourth Crusade in 1204 under Alexios IV Angelos.

The Despotate of Epirus was one of the Greek successor states of the Byzantine Empire established in the aftermath of the Fourth Crusade in 1204 by a branch of the Angelos dynasty. It claimed to be the legitimate successor of the Byzantine Empire, along with the Empire of Nicaea and the Empire of Trebizond, its rulers briefly proclaiming themselves as Emperors in 1227–1242. The term "Despotate of Epirus" is, like "Byzantine Empire" itself, a modern historiographic convention and not a name in use at the time.