Commodore Mendez
In dress uniform.
José I. Mendez was a 23rd century Starfleet officer. By 2267 he had reached the rank of Commodore.
That year, he replaced Commodore Stone as portmaster of Starbase 11. In this capacity, Mendez oversaw the care of Fleet Captain Christopher Pike when the latter was hospitalized at the starbase.
Shortly thereafter, Mendez greeted Captain James T. Kirk and Commander Spock when the USS Enterprise supposedly received a message to return to Starbase 11. Mendez denied sending such a message. It was soon revealed that Spock had falsified the message as part of a scheme to return Pike to Talos IV.
After Spock took command of the Enterprise and set a course for Talos IV, Mendez apparently traveled with Kirk aboard a shuttlecraft in pursuit of the starship. Mendez would then seem to preside over Spock's subsequent court martial aboard the ship. It was later revealed, however, that the Mendez aboard Enterprise and the shuttle was only an illusion, created by the Talosians to prevent Kirk from regaining command of the starship before it reached Talos IV. (TOS: "The Menagerie, Part I", "The Menagerie, Part II")
Background
The character's middle initial was visible on paperwork visible in closeups, and spoken by Uhura at the end of Part II. The commodore was played by Malachi Throne, who had previously provided the voice of the Keeper in TOS: "The Cage". His casting on this episode was fortuitous (or finagled) because there were several new lines written for the Keeper that he needed to record.
In the non-canon comic book Alien Spotlight: "Orions", Mendez acts as a contact for Pike at Starfleet, giving him information about Muso, a suspicious Tellarite.