Origin
Star Trek Canon Special Note

Not everything listed in the origin is Canon. That is because only television shows and movies are considered canon. This being a comic website there are many things here that are not canon. So unless it is contradicted in film it should be listed as part of the character biography.
Clark Terrell was born in Vancouver, British Columbia, Earth, in 2233. He grew up with stories from his great-grandfather about how his great-grandfather struggled for the right to vote, which stayed with young Terrell. He served the United Federation of Planets, entering Starfleet Academy at eighteen, and by 2254 was captain of the Academy’s wrestling team. His first cadet training mission was aboard the USS Gallant in 2254. He volunteered to serve with the landing party aiding a trapped team of scientists. He helped rescue them all from a space station damaged by meteors and knocked into a decaying orbit, and was awarded a citation for conspicuous bravery.
Early Starfleet Career

Terrell graduated from the Academy in 2255. His first assignment was junior helmsman aboard the USS Columbia. He was promoted in 2257 to lieutenant, junior grade and made chief helmsman of the ship.
Two years later, he became second officer aboard the USS Ardent. In 2261, he was stranded on Derus VI when the orbiting Ardent was destroyed by Orion pirates. After 4 year, he was recovered by a rescue team that discovered Terrell had established exclusive trade rights and an alliance with the natives. In recognition of these achievements he was awarded the Palm Leaf of Derus and Federation Star for Distinguished Service, and promoted to lieutenant commander.

In 2265, Commander Terrell was first officer aboard the scout starship, USS Sagittarius, assigned to Starbase 47 with Project Vanguard. In 2273, he served aboard the USS Pacifica as first officer, and was seen as an expert on first contact situations after successes on Yuria III, Olaras Prime, Mizar IV, and with the Pilurran Colonies, for which he was awarded the Four Palm Leaf and the Palm Cluster. He became Captain Terrell commander of the Pacifica in 2275, following Captain Mahtani’s promotion to admiral.
The Reliant Mission

Captain Terrell became commanding officer of the USS Reliant in 2282, serving as election monitor on the planet Mestiko. When the mar-Atyya’s troops threatened the use of deadly force to stop the voting, Terrell talked down their leader, ensuring a successful vote over a global media link, motivated in no small part by his great-grandfather’s experiences.

In 2285, Terrell and the Reliant were assigned to support Project Genesis, surveying planets in search of a lifeless testbed for the Genesis Device. While surveying the surface of planet Ceti Alpha V, which they believed to be Ceti Alpha VI, Terrell and first officer, Pavel Chekov were captured by the human Augment Khan Noonien Singh, whom James T. Kirk had exiled there eighteen years earlier along with Lieutenant Marla McGivers and 71 Augment followers.
Terrell and Chekov were interrogated in Khan’s quarters, the grounded SS Botany Bay, with parasitic Ceti eels. Entering through the ear canal, they twined about their victims’ cerebral cortexes, allowing Khan to control the men through suggestion. Khan first used them to take control of the Reliant, stranding the crew on the planet. After attacking the Regula I space station, Khan ordered Terrell to the Genesis cave within the planet Regula, to kill Admiral Kirk. Terrell was able to resist Khan’s influence, however, and turned his phaser on himself rather than kill a fellow officer.

Khan would not long survive Terrell, as Kirk lured the ancient warlord into the Mutara Nebula. Letting Khan’s ship overshoot his, Kirk then fired on the Reliant. As he died, Khan had activated the Genesis device, wiping out everything Terrell had seen on his final mission: the Reliant, Regula I, the planet Regula, and the Nebula itself, leaving the Genesis planet and it’s developing life in its wake.
Creation

Clark Terrell was created for the motion picture Star Trek II, and was played by Paul Winfield. In the shooting script for the film, Terrell is revealed to be an old friend of Dr. Leonard McCoy. This dialogue did not make the final cut, but does appear in the novelization. His early adventures are included in the Star Trek: Vanguard eight novel series.