Keratsa of Bulgaria

Keratsa of Bulgaria was the daughter of Tsar Ivan Alexander of Bulgaria and his second wife, a converted Jewess, Theodora. She was born in 1348.

On 17 August, 1355 Keratsa was betrothed to the future Emperor Andronikos IV Palaiologos. The marital document issued by the Patriarchate stated that "it would be beneficial to the Christians: Byzantines and Bulgarians, and pernicious to the infidels (the Turks)".

Keratsa married Emperor Andronikos IV Palaiologos of Byzantine (1376 - 1379) and became Empress of the Byzantine Empire. The marriage produced three children, one son and two daughters. Their son became Emperor John VII Palaiologos of Byzantium. John VII Palaiologos was Byzantine Emperor for five months in 1390.

She spend the later part of her life as a nun under the name Mathissa. She died in 1390.