Third officer

A third officer is an officer aboard a starship who is fourth in line of command of the vessel after the captain. In Starfleet the position was sometimes held by the security chief or tactical officer, and was typically filled by a lieutenant or lieutenant commander.

In 2257, Lieutenant James T. Kirk attempted to contact the third officer of the USS Farragut (NCC-1647) after his attempts to contact Captain Garrovick, First Officer Tolan and the ship's second officer had proven unsuccessful in the wake of an attack on the Farragut by the dikironium cloud creature.