Doukas, Latinized as Ducas (Greek: Δούκας; feminine: Doukaina/Ducaena, Δούκαινα; plural: Doukai/Ducae, Δούκαι), from the Latin tile dux ("leader", "general", Hellenized as doux), is the name of a Byzantine Greek noble family, whose branches provided several notable generals and rulers to the Byzantine Empire. The continuity of descent amongst the various branches is not clear though, and historians generally recognize several distinct groups of Doukai based on their occurrence in the contemporary sources. According to Demetrios I. Polemis, who compiled the only overview work on the bearers of the Doukas name, in view of this lack of genealogical continuity "it would be a mistake to view the groups of people designated by the cognomen of Doukas as forming one large family".