who is Constantine XI Palaiologos?
Helena Dragaš: Helena Dragaš (Serbian: Јелена Драгаш, "Jelena Dragaš" , Greek: , "Elenē Dragasē"; c. 1372 – 23 March 1450) was the empress consort of Byzantine emperor Manuel II Palaiologos and mother of the last two emperors, John VIII Palaiologos and Constantine XI Palaiologos.
i don't know