Starbase 12 was a Federation starbase in the Gamma 400 system and was close to the planets Ma-Bu-VI and the Ceti Alpha system. It was located in the Beta Quadrant.
Starbase 12 was one of the most important outposts in the Federation as it was in reach of both the Klingon and Romulan empires, and located near the Federation-Klingon border and the Orion Neutrality Area.
In 2167, Starbase 12 was under the command of Admiral Uttan Narsu.
In 2267, James T. Kirk originally set course for Starbase 12 with the SS Botany Bay in tow.
In 2364, the starbase was inexplicably evacuated for two days. Starfleet Command gave no explanation for this action. Captains Walter Reed, Rixx, and Tryla Scott saw this as further evidence of a conspiracy within Starfleet.
In 2366, the USS Enterprise-D underwent a one-week refit at Starbase 12, following its exhausting mission at Gemaris V.
In 2369, when Lieutenant Aquiel Uhnari and Klingon commander Morag were believed to be coalesenct organisms, these two were supposed to be brought to a secure medical facility on Starbase 12.