Epistates

An epistates (ἐπιστάτης) in ancient Greece was any sort of superintendent or overseer. In Hellenistic kingdoms generally, an epistates is always connected with a subject district (a regional assembly),  where the epistates, a resident representative, exercised control and collected taxes on behalf of the king.

Military use
In military texts, an epistates (the one who stands behind) is the man behind a protostates (the one who stands first/in front). The phalanx was made up of alternate ranks of protostates and epistates. Thus, in a file of 8 men, the protostates were the men in positions 1,3,5, and 7, while the epistates occupied positions 2,4,6, and 8.

New Testament usage
The word Epistates is also used in "common" Koine Greek and in the Greek New Testament to refer to Christ. This word is translated into English as 'master,' but that is a simplistic translation. The word might be better understood as belonging to the set of Greek words meaning visitor or divine visitation (episkope), letter of instruction (epistole), as well as guardian or caretaker (episkopos), which was a word later translated as bishop. See Luke 5:5 for an example of textural usage.