Died 991 in Thrace. Byzantine military commander.
In 970, Sclerus repulsed an attack on Constantinople by the Kievan prince Sviatoslav Igorevich. On three occasions, Sclerus rose up against Emperor Basil II. The first revolt, which began in 976, was crushed in 979 by the Byzantine military commander Bardas Phocas and by the ruler of the Tao-Klardzheti Principality, David III. In a conspiracy with Bardas Phocas, Sclerus rose up again in 987 but was betrayed by Phocas, who imprisoned him. Sclerus made one last attempt in 989, after the death of Phocas, but later that year was forced to surrender unconditionally to Basil II.