Omurtag (or Omortag) is a Great Khan (Kanasubigi) of Bulgaria from 814 to 831.

He is known as "the Builder".

In the very beginning of his reign, he signs a 30-year peace treaty with the neighboring Eastern Roman Empire that remains in force to the end of his life.

Omurtag successfully copes with the aggressive policy of the Frankish Empire to take Bulgaria's northwestern lands and suppresses the unrest among several Slavic tribes.

He makes administrative reforms that increase the power and the authority of the central government.

His reign is marked with a strong development of Bulgarian architecture with a number of significant construction projects.