Konstantin Dejanović, also known as Constantine Dragaš (fl.

1365-1395) was a Serbian magnate that rules a large province in eastern Macedonia under Ottoman suzerainty, during the fall of the Serbian Empire.

He succeeds his older brother Jovan Dragaš, who has been an Ottoman vassal since the Battle of Maritsa (1371) which had devastated part of the Serbian nobility.

The brothers have their own government and mint coins according to the Nemanjić style.

His daughter Jelena marries East Roman (Byzantine) Emperor Manuel II Palaiologos in 1392.

He falls at the Battle of Rovine (17 May 1395), serving the Ottomans against Wallachia, fighting alongside Serbian magnates Stefan Lazarević and Marko Mrnjavčević.

Constantine's grandson, the final Byzantine Emperor Constantine XI, is named after him, and will even use the name Dragaš.