Security Chief

The security chief (or chief of security) is the officer in charge of the security division of a starship or starbase.

In the Earth Starfleet, the armory officer was in charge of a ship's security department.

In the mid-23rd century Federation Starfleet a security chief, like Lieutenant Commander Giotto of the USS Enterprise, was not necessarily a bridge officer. (TOS: "The Devil in the Dark")

In the 2270s, the role of security chief was combined with that of the chief tactical officer. The chief tactical officer could be a separate position or be combined with that of helmsman or navigator. (Star Trek: The Motion Picture; Star Trek V: The Final Frontier; Star Trek VI: The Undiscovered Country)

In the 24th century, with helm and navigation consolidated in the new flight controller position, the chief tactical officer fulfilled the role of security chief. (TNG: "Encounter at Farpoint") Aboard the USS Voyager, Lieutenant Tuvok, as security chief, had thirteen department heads report to him every day on ship's protocol. (VOY: "Scientific Method")

On some starbases, such as Deep Space 9, the chief of security was a separate position from the tactical officer.