Omurtag (Bulgarian: Омуртаг [omurˈtak]) is a town at the eastern foot of Stara Planina in northeastern Bulgaria, part of Targovishte Province, situated at 525 m above sea level.

[1] A notable natives are Aleksandar Aleksandrov, one of the two Bulgarian cosmonauts, and Viktor Yosifov, captain of the Bulgaria men's national volleyball team.

The first written evidence of the modern town dates from the 17th century, when it was mentioned as the kaza centre Osman Pazarı in Ottoman tax registers.

Osman Pazarı was liberated from Ottoman rule on 27 January 1878 by Russian troops under Johann Casimir Ehrnrooth during the Russo-Turkish War of 1877–78.

Most of the Turkish inhabitants of the town left and were replaced by Bulgarians from around Tran and Kyustendil.