In 2375, during the Dominion War, he was assigned to AR-558, a planet that the Federation Alliance had captured from the Dominion. His commanding officers were Captain Loomis and Commander Parker. Fellow members of his unit included Reese, Vargas and Nadia Larkin.
Eight months later, the majority of the original members assigned to protect the planet’s communication array were dead, including Loomis and Parker. Larkin now commanded the troops. Kellin was killed in the final Jem’Hadar attack against AR-558 before the arrival of reinforcements and relief from the USS Veracruz. (DS9: “The Siege of AR-558“)
Kellin was played by Babylon 5 and Lost in Space star Bill Mumy. The actor had wanted to appear on Star Trek: Deep Space Nine ever since the show’s first season, and was offered many alien roles. He waited until he was offered a Human role.
Charles William “Bill” Mumy Jr. (born 1 February 1954; age 58), sometimes credited as Billy Mumy, is an actor from San Gabriel, California, who played Crewman Kellin in the Star Trek: Deep Space Nine episode “The Siege of AR-558“. Mumy had wanted to appear on the show for some time prior to this episode but he only wanted to play a Human, as he had worn alien makeup for years as a cast member of Babylon 5. (Star Trek: Deep Space Nine Companion)