He had pale skin, jet black tightly-curled hair, and a trimmed beard.
Prior to 2261, Carmody was a lieutenant commander and was in command of USS Chafee, an explorer scout ship. When dilithium was detected on the surface of Delar Seven, near Klingon territory, Carmody beamed down with a landing party. But Klingons had incited a civil war among the local inhabitants, and his crew walked into a battle. When a member of the landing party was wounded, Carmody responded by killing dozens of the inhabitants with his phaser. His crew detained him and returned to Chafee. Had the ship returned to Federation space, Carmody would have been court martialed for willful violation of the Prime Directive. But USS Chafee was captured shortly thereafter by the Klingons, who discovered Carmody in the brig. He agreed to work with them.
In the 2260s, Carmody assumed the identity of Premier Kaulidren of Chyrellka and engaged in a plot to destabilize the region. He had a dozen large surveillance Chyrellkan ships built to blockade the nearby colony on Vancadia.
In 2270, when the USS Enterprise was sent to mediate the dispute between Chyrellka and its colony, Kaulidren insisted on docking his space shuttle on the hangar deck, ostensibly because he was afraid of transporters, but in reality so he could have his ally Benjamin Finney sneak aboard and insert a virus into the ship’s main computer to relay false information to the bridge. The plan was to discredit Starfleet and Kirk by forcing him unwittingly to break the Prime Directive and destroy a helpless shuttle full of Chyrellkans. Also, the computer virus would be spread, allowing Klingon ships to disable Starfleet ships at will. But the tampering was discovered, and when the Enterprise's systems cleared, Carmody fled in a small, warp-powered Klingon ship at warp eight out of the system. But its engines overloaded and the ship self-destructed, with Carmody presumed dead. (TOS novel: Renegade)