Isaac II Angelos or Angelus was Byzantine Emperor from 1185 to 1195, and co-Emperor with his son Alexios IV Angelos from 1203 to 1204. In a 1185 revolt against the Emperor Andronikos Komnenos, Isaac seized power and rose to the Byzantine throne, establishing the Angelos family as the new imperial dynasty.

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.