Modern Greek military ranks are based on Ancient Greek and Byzantine terminology.
In the army and air force, these names are often based on the unit or post that a holder of each rank usual commands. For example, a is in charge of a , which is derived from an Ancient Greek word translatable as "command", "order", or "class", and in modern Greek is a unit equivalent to a battalion in other armies; hence a modern is a rank equivalent to major in other armies. Similarly, a normally commands a (a word that originally meant ""), which in Ancient Greece was a 100-strong hoplite unit, but in modern Greek usage is equivalent to an infantry company. Hence a is the equivalent of a captain in other armies, and the modern Greek equivalent of an army first lieutenant is the modern neologism : literally, "sub-captain". Likewise, the modern Greek equivalent of a sergeant is a .
The suffixes and (or ), which are often found in Greek rank names, are derived from the roots "to lead" and "to rule", respectively.
Officer ranks in the Army retain the style introduced in 1970, with the flaming grenade replacing (since 1975) the phoenix introduced by the Regime of the Colonels in 1973. Navy officer ranks retain the structure introduced in 1936. The Hellenic Air Force, is the youngest of the three services (founded in 1930). Its insignia are based on the British Royal Air Force, while it uses Army rank titles when translated to English.
Non-commissioned officers in the Greek armed forces are separated into three streams:
NCO ranks (excl. OR-9 and conscript ranks) have undergone some changes through the years, the latest being in 2004. In the army PNCOs are designated by having two arcs above their chevrons, whereas LTVs have no arcs. In the navy, NCO ranks have undergone changes since 1975. In the navy PNCOs are designated by having two arcs above their chevrons, whereas LTVs have one arc. In the air force PNCOs are designated by having two arcs above their chevrons, whereas LTVs have no arcs.
Graduates of PNCO Schools will no longer automatically be promoted to OF-1 after 19 years of service. Instead, a new rank structure will be instituted, with a starting rank of , outranking all volunteers from graduation. Promotions to and above will be effectuated by selection, like flag officers, after the 35-year retirement limit. Promotions to and will not necessitate time served in the preceeding rank.
PNCOs may be transferred to the officer corps under certain conditions (holding a degree, 14 years of service, etc.), but they no longer retain their specialisation. Starting in 2027, all three PNCO schools will confer degrees equivalent to university degrees, like officer academies.
PNCO ranks will be altered as follows:
Volunteer ranks are also split in two (with the exception of the rank of ). Volunteers will no longer be promoted to . Promotions to E9-E12 will be effectuated by selection, like flag officers, after the 35-year retirement limit. They may be transferred to the Corps of Permanent NCOs to fill organizational positions if they have completed a specific period of service (e.g., 15 years) and meet academic criteria.