Captain James Tiberius Kirk. (Voice by William Shatner).
Commanding officer of the Constitution-class Federation starship Enterprise from 2264 to 2270. Easily the most famous starship captain in the history of Starfleet, Kirk was a natural leader and hero. He was handsome, young, driven and entirely professional to the point of almost forfeiting any personal life. Chief among his recreations was enjoying the company of female companions, although he never settled down with any woman. Kirk was born in 2233 in Iowa on the planet Earth. Kirk maintained a professional detachment from his crew but considered First Officer Spock, ship's doctor Leonard McCoy and Chief Engineer Scott as the best of friends, owing his life to each of them on several occasions.

In 2269 he almost died when the women of Taurus II drained he and his landing party of their life-energy. ("The Lorelei Signal"). on stardate 5143.3 Kirk was rendered unconscious and temporarily replaced by a shape-shifting Vendorian. While in Kirk's form the Vendorian violated Federation law by entering Romulan space. ("The Survivor"). On stardate 1254.4 he and his crew were placed on trial by the inhabitants of Megas-tu, but were released partly due to the help of the charismatic Lucien. ("The Magicks of Megas-Tu"). Along with his crew, Kirk was reduced to Liliputian dimensions by the effects of spiroid epsilon waves while investigating a distress call from the Terratins on stardate 5577.3. ("The Terratin Incident"). Both Kirk and Spock were mutated into water-breathers on stardate 5499.9 by well meaning Aquans on the planet Argo. ("The Ambergris Element"). Because of his leadership abilities and adaptability, Captain Kirk was chosen by the Vedalans to lead an extraordinary mission to retrieve the Soul of Skorr in late 2269. His team was successful and a potential intergalactic conflict was averted. ("The Jihad").

In 2270 the crew of the Enterprise experienced accelerated reverse ageing. As a result of his growing too young, James Kirk was temporarily replaced as commander of the Enterprise first by Spock and then later by Commodore Robert April. After the starship returned to normal space. the crew were returned to their normal ages by use of the ship's transporters, and Kirk resumed as the Enterprise's captain. ("The Counter-Clock Incident").

Captain Kirk appeared in every episode of the animated series except "The Slaver Weapon." Kirk's middle name, Tiberius, was first revealed in the animated episode "Bem." and was mentioned again in STAR TREK VI: The Undiscovered Country (1991). During the Original Series it was not known what his middle initial, "T", stood for. William Shatner also portrayed Kirk in the original series and movies.

In William Shatner's 1994 memoir, STAR TREK Movie Memories, the actor who portrayed Captain Kirk's second set of STAR TREK memoirs, had some small mention of the animated STAR TREK series.