Demetrios Angelos Doukas (Greek: Δημήτριος Ἀγγελοδούκας), was ruler of Thessalonica with the title of Despot as a vassal of the Empire of Nicaea from 1244 until his deposition in 1246.
[9][10] In the aftermath of Klokotnitsa, Theodore's empire collapsed: within a few months most of Thrace, Macedonia, and Albania, fell under Bulgarian rule.
[11][12] Theodore's brother Manuel, who managed to escape from Klokotnitsa, now took over the throne in Thessalonica, ruling over a much-reduced domain as a vassal of the Bulgarian ruler.
Theodore made his way back to Thessalonica and overthrew Manuel, but as he was blind, he installed his oldest son John as emperor.
In terror, Demetrios fled to the citadel, but was persuaded to yield by his sister Irene, who had presented herself before Vatatzes and secured clemency for her brother.