The commodore in charge of Starbase 11 when Spock hijacked the Enterprise to carry Christopher Pike to Talos IV.
Mendez is the commodore commanding Starbase 11 when the Enterprise calls there and Spock learns that his former captain, Christopher Pike, has been left horribly disabled. Spock takes Pike aboard, seizes the ship by deception and sets course for Talos IV. Mendez and Kirk pursue the ship by shuttlecraft and are brought aboard.
Mendez then sits in judgement at Spock's court martial, held aboard the ship. At the end of the hearing it emerges that the Mendez on board was an illusion projected by the Talosians, and the real commodore, watching from the starbase, allows Pike to remain on Talos IV. He was played by Malachi Throne.