The Theme of Thrace (Greek: θέμα Θρᾴκης or θέμα Θρᾳκῷον) was a province (thema or theme) of the Byzantine Empire located in the south-eastern Balkans, comprising varying parts of the eponymous geographic region during its history.

Traditionally, it has been held that the theme (at the time primarily a military command) was constituted in c. 680, as a response to the Bulgar threat.

Another, called tourmarches tes Thrakes ("of Thrace") is also attested, possibly the strategos' deputy at Arcadiopolis.

Initially, the theme must have comprised most of the ancient Diocese of Thrace, except for the country along the Danube overrun by the Bulgars (Lower Moesia), but after the conquests of Krum (r. 803–814), Omurtag (r. 814–831), and Symeon (r. 893–927) the border moved by stages south of the Balkan Mountains to roughly the line of the present Bulgarian frontier with Greece and Turkey.

[6] From the eleventh century, Thrace and Macedonia appear to have been usually combined, as attested by numerous strategoi and judges (kritai) holding jurisdiction over both themes.