Develtos or Deultum was an ancient city and bishopric in Thrace. It was located at the mouth of the river Sredetska reka on the west coast of Lake Mandrensko, previously part of the Gulf of Burgas, and near the modern village of Debelt.

Michael Doukas Glabas Tarchaneiotes or Michael Tarchaneiotes Glabas was a notable Byzantine aristocrat and general. He served under emperors Michael VIII Palaiologos and Andronikos II Palaiologos in the Balkans, fighting against the Second Bulgarian Empire, Serbia, the Angevins of Naples and the Despotate of Epirus. He is also notable as the patron of several churches, most notably the Pammakaristos Church in Constantinople, where he was buried.