Topotērētēs was a Byzantine

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 technical term, meaning deputy or lieutenant

Lieutenant

A lieutenant is a junior commissioned officer in many nations' armed forces. Typically, the rank of lieutenant in naval usage, while still a junior officer rank, is senior to the army rank...

 (literally "place-warden"). As such, it was used in different ways throughout the Empire's history. In the 9th-11th centuries, the topotērētēs was the deputy of senior military commanders of the themata, the tagmata and the Byzantine navy

Byzantine navy

The Byzantine navy was the naval force of the East Roman or Byzantine Empire. Like the empire it served, it was a direct continuation from its imperial Roman predecessor, but played a far greater role in the defense and survival of the state then its earlier iterations...

. The topotērētēs was usually placed in command of one half of the respective unit. In the early 12th century, topotērētai are found as commanders of small regions and fortresses, while in the late Palaiologan period, the term was used for representatives of the Patriarch of Constantinople

Patriarch of Constantinople

The Ecumenical Patriarch is the Archbishop of Constantinople – New Rome – ranking as primus inter pares in the Eastern Orthodox communion, which is seen by followers as the One, Holy, Catholic, and Apostolic Church....

in sees that now lay outside the Byzantine Empire's borders.