2. Sub-Commander Tal (Jack Donner: "The Enterprise Incident")
When Captain Kirk begins to act erratic and orders the Enterprise across the Neutral Zone, it is the Romulan Sub-Commander Tal who addresses Kirk and surrender after the starship is surrounded. Tal does so fearlessly, despite his lesser rank in the Romulan military hierarchy. He also appears to be quite young, which means his intelligence and bravery probably brought him up through the ranks rather quickly.
When Tal's commander tries to prevent Spock's escape from the Romulan ship via the transporter, she finds herself on the bridge of the Enterprise. Tal does not abandon her, however; he remains loyal to her. He watches the events via the ship's viewscreen, and when the commander orders him to destroy the Enterprise, the screen ominously goes black.
Tal's expression when he sees Kirk diguised as a Romulan is sort of amusing--he looks like he licked a lemon! You have to wonder if Tal got his commander's job after Kirk and the crew managed to steal and use the cloaking device!