Tarn Mison, a male Human originating from Las Lagon, initially worked as a pilot for the Imperial forces, and also engaged in smuggling. He later switched his allegiance to the Rebel Alliance after witnessing the Empire's mass execution of colonists on Farbinda III. By the time period of 3 ABY, Mison was stationed at Echo Base, the headquarters of the Rebellion, located on the ice planet Hoth.
During the Battle of Hoth, Mison served as the gunner for Tycho Celchu, using the call sign Rogue Five. Following this, Mison was part of a team of six Rebel pilots who provided X-wing starfighter escort for the GR-75 medium transport named Bright Hope as it attempted to break through the Imperial Navy blockade in orbit above Hoth. Despite their best efforts, the Bright Hope was destroyed during its attempt to escape the blockade.
Tarn Mison, a male Human, was born on the planet of Las Lagon, situated within the Inner Rim. As he grew up, Mison acquired piloting skills, gaining recognition as a skilled bush pilot. Eventually, Mison enlisted in the Galactic Empire and served as a pilot.
Later, Mison transitioned to smuggling, operating along the Shipwrights' Trace hyperlane. During the Galactic Civil War, he accepted a contract to transport supplies to Farbinda III, a celestial body where a group of conscientious objectors had established a colony. Upon his arrival, he witnessed an Imperial strike team rounding up the unarmed local population. Mison was a witness to the summary execution of the colonists by the Imperials.
Deeply disturbed, Mison contemplated these events for several months before deciding to join the Alliance to Restore the Republic shortly after the destruction of the first Death Star at the Battle of Yavin in 0 BBY. For a period, Mison served the Rebellion at Massassi Station on the moon of Yavin 4, prior to the Alliance's evacuation of the base six months after the Battle of Yavin.
By 3 ABY, Mison, holding the rank of lieutenant, was assigned to Echo Base, the Alliance High Command headquarters on the ice planet Hoth. He happened to be passing through the facility's main transport hangar when Captain Shawn Valdez was giving instructions to his subordinates regarding the base's evacuation plan in anticipation of an imminent Imperial invasion, just before the Battle of Hoth.
Mison was recruited into the hastily formed Rogue Group, a team of pilots and gunners selected from Rogue Flight, Blue Squadron, and Green Squadron. Rogue Group's mission was to fly snowspeeders to defend against the Imperial AT-AT walker assault, providing the Alliance forces with enough time to evacuate the planet. Mison was paired with Tycho Celchu, serving as his gunner with the call sign Rogue Five.
Both Celchu and Mison survived the battle that followed. During the final stages of the evacuation, Mison, along with pilots Wedge Antilles, Derek "Hobbie" Klivian, and Wes Janson, was among the six Rebel pilots who flew T-65 X-wing starfighters as escorts for the GR-75 medium transport Bright Hope. The Bright Hope was the last Rebel transport to depart from the besieged Echo Base, alongside the GR-75 medium transports Thon's Orchard and Dutyfree.
However, Mison's escort detail was unable to guide the Bright Hope through the Imperial Navy blockade that awaited in Hoth's orbit. A coordinated attack by Imperial Star Destroyers and the Mist Hunter, the ship used by bounty hunters Zuckuss and 4-LOM, nearly destroyed the Bright Hope before it could reach the safety of hyperspace. Realizing that there was nothing they could do to save the Bright Hope and that a rescue attempt for any potential survivors was impossible, Mison and the five escorting X-wing pilots escaped into hyperspace themselves.
Despite the damage inflicted on the Bright Hope, many of the transport's passengers were successfully evacuated to safety. Similarly, both Thon's Orchard and Dutyfree also managed to safely evacuate.
Mison wore the standard Rebel flight suit and a flight helmet while serving as a Rebel pilot.
Tarn Mison's initial appearance was as a Rebel pilot extra in the 1980 original trilogy film, Star Wars: Episode V The Empire Strikes Back. Michael Pangrazio, an uncredited matte artist from Industrial Light & Magic, played Mison in the film. The other Rebel characters in the Mison scene were also ILM artists, including Ralph McQuarrie, Joe Johnston, and Harrison Ellenshaw. Their scene was filmed as part of pickup shots at Industrial Light & Magic in California on February 9, 1980, and was completed after ten takes.
The character of Mison was first given a name and a brief backstory on the "Lieutenant Tarn Mison" card in the 1998 Special Edition Limited expansion set for Decipher's Star Wars Customizable Card Game. The card's information retconned Mison as one of the X-wing pilots escorting the Bright Hope off Hoth in the 1996 short story, "Of Possible Futures: The Tale of Zuckuss and 4-LOM," featured in Tales of the Bounty Hunters.
In 2012, Jason Fry's reference book, The Essential Guide to Warfare, identified Mison as the gunner of Rogue Five during the Battle of Hoth. Because the book officially confirms Mison's membership in Rogue Group, the character also makes an indirect appearance in the first issue of the The Empire Strikes Back manga adaptation, published on January 27, 1999, which depicts all twelve airspeeders of Rogue Group.