Helena Palaiologina, Despotitsa of Serbia

Helena Palaiologina was a Byzantine princess who married Serbian Despot Lazar Brankovi, who ruled from 1456 until his death in 1458. After Smederevo fell to the Ottoman Turks onJune 1459, she fled Serbia for the Greek island of Leukas, where she converted to Catholicism. She later became a nun, assuming the name of Hypomone .

Helena was born in the Despotate of the Morea in 1431, the eldest daughter and child of Thomas Palaiologos, Despot of the Morea and Catherine Zaccaria of Achaea. She had two younger brothers, Andreas Palaiologos and Manuel Palaiologos, and a sister, Zoe, who would become the wife of Ivan III of Russia. Her maternal grandparents were Centurione II Zaccaria and Creusa Tocco. Her first cousin, also Helena Palaiologina, became Queen consort of Cyprus.

Source: Wikipedia