- The episode gave Garth no other name. Fan fiction has sometimes assumed that this is his surname. FASA materials refer to him as "Kelvar Leonard Garth" (FASA RPG: The Four Years War).
- Different sources have Garth in command of different vessels at Axanar. FASA had him as captain of the USS Xenophon, while the TOS novel: Garth of Izar had him in command of USS Heisenberg.
During the Four Years War, Garth commanded Task Force Constitution from USS Constitution. Ships assigned to the task force included USS Avenger and USS Illustrious. (Star Trek: Avenger: "Early History of USS Avenger")
- In Orion Press continuity, Garth was commanding officer of USS Lexington during this time.
- In Star Trek: The Four Years War continuity, Garth was commanding officer of the Xenophon and, later, the 7th Battle Group of the First Fleet.
In the early 2260s, after a transporter accident at Antos IV, the indigents of that world taught Garth to heal through cellular metamorphosis. This apparently drove him mad and Garth attempted to destroy the Antosians but was prevented from doing so. However, Garth killed both his executive officer and second officer. (TOS novel: Garth of Izar)
In 2268, when USS Enterprise was delivering a new therapy to the colony, Garth masqueraded as Governor Donald Cory and kidnapped both Kirk and Spock. After their release, the therapy was administered to Garth.