Lieutenant Kaplan was a male Human Starfleet officer who lived during the mid-23rd century. He served in the operations division, aboard the USS Enterprise under Captain James T. Kirk, as one of the ship's security officers.
In 2267, Kaplan was one of four security officers that joined the landing party of nine that surveyed the planet Gamma Trianguli VI. When Spock detected Akuta observing their position, Kirk indicated to Kaplan to swing around to locate the native, but were unsuccessful.
After being unable to beam back up to the ship, Kirk told Kaplan to take the post. While at his position, he was vaporized by a lightning strike during an electrical storm created by Vaal, the computer that controlled the planet's climate.