Third sergeant is typically a non-commissioned officer rank, used in some countries.
Third sergeant is a specialist rank in the Singapore Armed Forces.
[6] In combat units, third sergeants are usually section commanders working with the supervision of a commissioned officer holding the appointment of platoon commander, and under the supervision of a senior specialist holding the appointment of platoon sergeant.
Third sergeants in the SAF also hold equivalent junior commander appointments, assisting a platoon section of enlistees.
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 competency and manpower.