Third sergeant is a specialist rank in the Singapore Armed Forces. Third sergeants are the most junior of specialists (Non-commissioned officer). The 3SG rank insignia is three chevrons pointing down, common by all specialists, without any chevrons pointing up.
In combat units, third sergeants are usually section commanders working directly under the supervision of a commissioned officer holding the appointment of platoon commander, and with the assistance of a senior specialist holding the appointment of platoon sergeant.
Third sergeants in the SAF also hold equivalent junior commander appointments, supervising a platoon section of enlisted men. For example, transport supervisors, commonly known as the MT (motor transport) section commanders, and such as battalion company quartermaster sergeant. In other armies, this position is usually held by staff sergeants and above, while in Singapore, conscript soldiers holding these appointments are of the rank of third sergeant due to manpower constraint.
The rank of third sergeant is also utilized by the armed forces of Brazil.