Tsar Michael Asen

Michael Asen IV (in English: Michael Asen IV of Bulgaria; c. 1322–1355) was the firstborn son of Tsar Ivan Alexander (r. 1331–1371) from his marriage to Theodora Basarab, daughter of the Bulgarian voivode Ivanko I Basarab. He was born around 1322 and died in battle in 1355. From 1336 he assisted his father in governing the country as co-tsar in its Tarnovo region. He married  the Byzantine princess Irene Palaiologina; according to some sources the marriage was childless, while according to others it produced three children.