John Komnenos Doukas

John Komnenos Doukas (c. 1214–1244), eldest son of Theodore Komnenos Doukas, was captured by Tsar Ivan Asen II at Klokotnitsa in 1230 and freed in 1237 after his sister Irene married the tsar. His blinded father then ousted Manuel from Thessalonica and installed John as ruler.

In 1239 Manuel returned with Nicaean support and took Thessaly, which Theodore and John accepted. John used the imperial title by 1241, when Ivan Asen's death ended Bulgarian protection of Thessalonica; in 1242 the Nicaean emperor John III Vatatzes marched on the city and forced him to drop the title and accept the rank of despot under Nicaean suzerainty.

He showed little talent for governing and was said to wish to become a priest. On his death in 1244 his brother Demetrios succeeded him.