The Harbor of Eutropius (Greek: λιμήν Εὑτροπίου) was an artificial harbor east of Chalcedon (modern-day Kalamış), along the coast of Asia Minor, during the Byzantine Empire. It was constructed by order of Byzantine Emperor Justinian (r. 527–565), made of large moles of black stone. It was likely the smallest of the harbors opposite the Byzantine capital Constantinople, and served an unknown function. The harbor was the location for the execution of Emperor Maurice (r. 582–602), along with his sons, and later, the female members of his family. During the Siege of Constantinople of 717–718, the harbor was one of the landing grounds of the invading Umayyad forces. With the expansion of the maritime districts of nearby Kalamış and Fenerbahçe in modern times, nothing remains of the harbor.