First sergeant

First sergeant (1SG) is typically a senior non-commissioned officer rank, used in many countries. In NATO armed forces the rank is on OR8 level.

Singapore

First sergeant is a specialist in the Singapore Armed Forces. First sergeants are the most senior of the junior specialists, ranking above second sergeants, and below staff sergeants. The rank insignia for a first sergeant features the three chevrons pointing down shared by all specialists, and two chevrons pointing up.

In combat units, first sergeants are very often platoon sergeants, or given the responsibility for independently operating detachments of support weapons. They are often given instructional billets as well in training schools. First sergeants normally answer to the company sergeant major, assisting the latter in the mentorship, guidance and command of the more junior specialists (Third and Second Sergeants) who are section commanders.

United States

In the United States, a first sergeant generally serves as the senior enlisted advisor (SEA) of a unit, such as a company, battery, troop, or a USAF squadron or higher level unit. (USA and USMC squadrons and battalions, as well as all higher level units, have a Command Sergeant Major [USA] or Sergeant Major [USMC] as the SEA). (While the specifics of the title may differ between the United States Army, Marine Corps and Air Force, all first sergeants can be identified by the presence of a lozenge-shaped (colloquially "diamond") figure on their rank insignia.