Michael Asen IV of Bulgaria

Michael Asen IV (c. 1322–1355) was the eldest son of Tsar Ivan Alexander of Bulgaria and Theodora of Wallachia. Soon after his father took the throne in 1331, the boy was crowned co-emperor and designated heir.

In 1339 he married Maria, renamed Irene, daughter of the Byzantine emperor Andronikos III Palaiologos. When the Ottomans invaded Bulgaria in 1354–1355, heading for Plovdiv and Sofia, Michael gathered the Bulgarians and met the Turks near Sofia.

An anonymous Bulgarian chronicle records heavy Bulgarian losses, Michael among the dead. The Ottomans took neither city and left Bulgaria alone until 1370, and folklore remembers the emperor's son as one of the brave who fell.