Thomas Preljubović was ruler of the Despotate of Epirus in Ioannina from 1367 to his death in 1384. Thomas was an unpopular ruler and is appraised very negatively by his contemporaries. On December 23, 1384 he was stabbed to death by his guards at dawn. The conspiracy of the faction which overthrew him involved his wife Maria Angelina who succeeded him.

The despot of Epirus was the ruler of the Despotate of Epirus, one of the successor states of the Byzantine Empire in the aftermath of the Fourth Crusade. The name "Despotate of Epirus" and the title "despot of Epirus" are modern historiographical names, and were not in use by the despots themselves. In the Byzantine Empire, the title of despot was a prestigious court title and did not designate rule over some specific territory. Though several of the early Greek rulers of the Epirote realm did use the title of despot, it was never in reference to the lands they governed, but instead in reference to their position in the imperial hierarchy.