Demetrius or Demetrios of Montferrat (Italian: Demetrio di Monferrato; Greek: Δημήτριος Μομφερρατικός, Dēmētrios Momferratikos), (Thessalonica, 1205 – 1230 in Amalfi), was king of Thessalonica from 1207 to 1224. The new Latin Emperor, Peter of Courtenay, was won over by the Lombard lords and invested William of Montferrat with the kingdom before leaving Italy. The Queen Mother Margaret fled to Hungary, but Demetrius apparently remained in place, while the Emperor Peter was captured and eventually executed by Theodore Komnenos Doukas in Epirus.