Theodore I Ducas

Theodore Komnenos Doukas
Ruler of Epirus, after 1224 Emperor of Thessalonica (self-proclaimed Byzantine emperor)
Electrum coin with Theodore (left) blessed by Thessalonica's patron, St. Demetrius
Reign	1215–1230
Predecessor	Michael I Komnenos Doukas
Successor	Manuel Komnenos Doukas
Died	c. 1253
Spouse	Maria Petraliphaina
Issue	John Komnenos Doukas Demetrios Angelos Doukas Anna Angelina Komnene Doukaina Irene Komnene Doukaina
Dynasty	Komnenos Doukas
Father	John Doukas
Mother	Zoe Doukaina

Theodore Komnenos Doukas (Greek: Θεόδωρος Κομνηνός Δούκας, Theodōros Komnēnos Doukas, Latinized as Theodore Comnenus Ducas, died c. 1253), was ruler of Epirus and Thessaly from 1215 to 1230 and of Thessalonica and most of the rest of Macedonia and western Thrace from 1224 to 1230. He was also the power behind the rule of his sons John and Demetrios over Thessalonica in 1237–46.

Theodore was the scion of a distinguished Byzantine aristocratic family related to the imperial Komnenos, Doukas, and Angelos dynasties. Nevertheless, nothing is known about Theodore's life before the conquest of Constantinople and dissolution of the Byzantine Empire by the Fourth Crusade in 1204. Following the fall of Constantinople, he served Theodore I Laskaris, founder of the Empire of Nicaea, for a few years, before being called to Epirus, where his bastard half-brother Michael I Komnenos Doukas had founded an independent principality. When Michael died in 1215, Theodore sidelined his brother's underage and illegitimate son Michael II and assumed the governance of the Epirote state. Theodore continued his brother's policy of territorial expansion. Allied with Serbia, he expanded into Macedonia, threatening the Latin Kingdom of Thessalonica. The capture of the Latin Emperor Peter II of Courtenay in 1217 opened the way to the gradual envelopment of Thessalonica, culminating in the city's fall in 1224.