Helena Palaiologina was a Byzantine princess who married Serbian Despot Lazar Branković, who ruled from 1456 until his death in 1458. After Smederevo fell to the Ottoman Turks on 20 June 1459, she fled Serbia for the Greek island of Lefkada, where she converted to Catholicism.

The Serbian Despotate was a medieval Serbian state in the first half of the 15th century. Although the Battle of Kosovo in 1389 is mistakenly considered the end of medieval Serbia, the Despotate, a successor of the Serbian Empire and Moravian Serbia, lasted for another sixty years, experiencing a cultural, economic, and political renaissance, especially during the reign of Despot Stefan Lazarević. After the death of Despot Đurađ Branković in 1456, the Despotate continued to exist for another three years before it finally fell under Ottoman rule in 1459.