The sebastos Constantine Doukas (Greek: Κωνσταντίνος Δούκας; died 8 April 1179) was a Byzantine general and provincial governor under Emperor Manuel I Komnenos.
His relation with the prestigious Doukas family is unknown.
[1] What little is known of him comes from a short biographical notice in a manuscript (Par.
According to it, in 1173 Emperor Manuel sent Constantine to help defend Ancona in Italy, a Byzantine ally, against a combined attack from Holy Roman Emperor Frederick I Barbarossa and the Republic of Venice.
The siege lasted for seven months, but Constantine successfully defended the city from capture.