Theodora Smilets (Bulgarian: Теодора Смилец) was a Bulgarian princess and queen consort of Serbia, the first wife of king Stefan Uroš III Dečanski of Serbia.

Theodora was the second daughter of Bulgarian tsar Smilets and his Byzantine wife, who in the histories was called just Smiltsena (Bulgarian: Смилцена; the wife of Smilets) without a name being given, but who was the daughter of sebastocrator Constantine Palaiologos and niece of Michael VIII Palaiologos.

Theodora was married to Serbian crown prince Stefan Uroš (later king) on 24 August 1296. They had two children:

• Stefan, later Stefan Uroš IV Dušan of Serbia
• Elena

In 1314, her husband's father, Stefan Milutin, quarreled with Stefan, and sent him to Constantinople to be blinded. Theodora and the family went with him and established a household there until 1320 when they were allowed to return. Theodora died 20 December 1322 at the royal residence at Zvechan, Kosovska Mitrovica. She was buried in the nearby monastery.