Military units and formations established in the 5th century

The Excubitors ( or , , i.e. 'sentinels'; transcribed into Greek as , ) were founded in as an imperial guard-unit by the Roman emperor Leo I the Thracian. The 300-strong force, originally recruited from among the warlike mountain tribe of the Isaurians, replaced the older as the main imperial bodyguards. The Excubitors remained an active military unit for the next two centuries, although, as imperial bodyguards, they did not often go on campaign. Their commander, the Count of the Excubitors (, ), soon acquired great influence. Justin I was able to use this position to rise to the throne in 518