Prōtostratōr (Greek: πρωτοστράτωρ) was a Byzantine court office, originating as the imperial stable master, which in the last centuries of the Empire evolved into one of the senior military offices. The female form of the title, given to the wives of the prōtostratores, was prōtostratorissa (Greek: πρωτοστρατόρισσα).
History and evolution
The title means "first stratōr", reflecting the office's initial nature as chief of the imperial taxis of the stratores ("grooms"), who formed a schola under the Count of the Stable. Although the existence of stratores is attested since Antiquity, the first direct mention of the office of the prōtostratōr dates to 765. During the middle Byzantine period (up to the mid-11th century), its official place in the hierarchy was not high, but its proximity to the emperor did facilitate a rapid rise, as exemplified by the future emperors Michael II and Basil I the Macedonian. The prōtostratōr had a prominent place in imperial ceremonies, riding beside the Byzantine emperor on processions, or even introducing foreign envoys at imperial audiences. In the 9th-11th centuries, his subordinates included the [basilikoi] stratōres, the armophylakes ("keepers of the armaments" or possibly "of the chariots", from armatophylakes), and three stablokomētes ("stable counts"). 
By the late Komnenian period, however, the post had risen considerably in importance: in the Komnenian army, the holder of the office was second-in-command of the army after the megas domestikos. Niketas Choniates equated the office with the Western marshal, and it appears to have been used interchangeably with it in the Latin Empire and the other Latin states formed after the Fourth Crusade. The office continued to exist during the Palaiologan period until the Fall of Constantinople in 1453. It remained one of the highest dignities of state, although from the late 13th century on, multiple persons could hold it.
- Michael II
- Basil I the Macedonian
- Alexios Axouch
- Alexios Doukas Philanthropenos
- Michael Doukas Glabas Tarchaneiotes
- Theodore Synadenos
- Giovanni Giustiniani
- Bury 1911, p. 117.
- Kazhdan 1991, pp. 1748–1749.
- Kazhdan 1991, p. 1748.
- Bury 1911, pp. 117–118.
- Bury 1911, p. 118.
- Van Tricht 2011, p. 180.
- Suny 1994, p. 35: "In the formation of his ruling apparatus, David employed the great eristavni, thus making them dependent on him. The eristavi of Svaneti, Iovane Vardanisdze, became the protostratori (later called amirakhori), the second-in-command of the army, and later was given the post of mechurchletukhutsesi, the director of finances."
- Bury, John B. (1911). The Imperial Administrative System of the Ninth Century: With a Revised Text of the Kletorologion of Philotheos. London: Oxford University Press.
- Guilland, Rodolphe (1967). "Le Protostrator". Recherches sur les institutions byzantines, Tome I (in French). Berlin: Akademie-Verlag. pp. 478–497.
- Kazhdan, Alexander (1991). "Protospatharios". In Kazhdan, Alexander. The Oxford Dictionary of Byzantium. New York and Oxford: Oxford University Press. pp. 1748–1749. ISBN 978-0-19-504652-6.
- Suny, Ronald Grigor (1994) . The Making of the Georgian Nation. Bloomington, Indiana: Indiana University Press. ISBN 0253209153.
- Van Tricht, Filip (2011). The Latin Renovatio of Byzantium: The Empire of Constantinople (1204-1228). Leiden: Brill. ISBN 978-90-04-20323-5.