Michail Asen (Bulgarian: Михаил Асен, variously also spelled in English as Mihail or Michael) was the eldest son of Tsar Ivan Alexander of Bulgaria from his marriage with Theodora of Wallachia.
After his father acceded to the throne in 1331, the young prince was proclaimed co-Emperor. He was to succeed his father under the name Michael IV Asen. The heir to the throne was the pride of the royal family and was said to possess "all virtues". He married Maria, renamed Irina, the daughter of Andronikos III Palaiologos.
In 1354 - 1355 the Ottoman Turks invaded Bulgaria and headed towards Plovdiv and Sofia. It is mentioned in an anonymous Bulgarian chronicle that Michail Asen gathered the Bulgarians and engaged the Turks near Sofia. The Bulgarians were defeated and suffered heavy casualties including Michail himself. But the battle was not in vain: the Ottomans failed to capture the cities and did not attack the country again until 1370. In the Bulgarian folklore is mentioned that the son of the Emperor perished with the death of the brave.