Stefan Dušan

(born 1308—died Dec. 20, 1355) King of Serbia (1331–46) and emperor of the Serbs and Greeks (1346–55). He deposed his father, Stefan Decansky, in 1331. The greatest ruler of medieval Serbia, he began a war of conquest against Byzantium in 1334, gaining control of Albania and Macedonia by 1346 and Epirus and Thessaly by 1348. Dušan reformed the Serbian administration on the Byzantine model and introduced a law code. His rule over former Byzantine lands was threatened by John VI Cantacuzenus, and his empire broke apart soon after his death.

Source: Encyclopedia Britannica