Gilkarg nar Kiranka was the only son of the Emperor Joor'rad nar Kiranka and as such, the Crown Prince and legal heir to the throne during the 2600s. He fathered two sons Ratha and Thrakhath (the latter who would succeed him as Crown Prince for a period due to the rite of Chosen Claw). Gilkarg had already risen to the rank of Kalralahr of the Kilrathi Fleet by the year 2634, the year in which the Kilrathi War broke out.
Envious of his father's glory during the Kilrathi-Varni War, he pushed politics towards war with the Terran Confederation in order to achieve his own glory, as it would be him who would lead the fleet. He participated in 3-day long court proceedings until the Emperor declared his decision for war, but Gilkarg was unsettled to see that Lord Vakka still had objections. Ratha accused him for cowardice but Gilkarg stopped him, saying that Vakka had laid down his ceremonial dagger as a proof of submission to the Emperor, and a blood challenge can't be made. Thrakhath aso made a sly comment against Vakka, but in display of crass disregard for decorum, Gilkarg did not discipline the cub.
Gilkarg countered Vakka's arguments and considerations; he insisted that more war means more glory. Regarding the Nephilim who threatened the Empire from the center of the galaxy, Ratha once more accused Vakka for cowardice, until Gilkarg ordered him to stop; Gilkarg however backed his son saying that the war against the Confederation would only make them stronger and more experienced as he doubted that they would form ever an aliance against the Nephlim (the Confederation would prefer the Empire as a buffer zone against the Nephilim). Regarding Vakka's warnings about the depth and robustness of the Confederation, Gilkarg insisted that the first blow would be so strong as to disable its power; if the Confederation intended to strike first, the Kilrathi woud do the trick of the haggin. urthermore, Gilkarg was backed by the Lords's lust for imediate battle and glory.
Gilkarg had a strong hatred for the humans of the Terran Confederation, and was charged with leading the assault that would destroy their empire. His first step in this grand plan was an attack on the human colony of McAuliffe, located on the frontier of the Vega Sector.
Gilkarg kept the attack secret until he could unleash his full fury on the human colonies at McAuliffe. It was this expert secrecy that prevented the Confed Fleet from discovering that the fleet they were expecting was four times its expected size. When the attack was launched, Gilkarg used shield-piercing torpedoes and an enormous number of starfighters to decimate Confed forces. After four days of intense fighting, several Confed ships are destroyed, but so are many of Gilkarg's, so he retreats to reorganize his forces. Despite a formidable and devastating resistance from the Confed Fleet, McAuliffe eventually falls and 250,000 colonists are imprisoned. The Enyo Engagement was also fought around this time, resulting in the fall of Enyo and the capture of another 250,000 colonists. All of these prisoners would be massacred by orbital guns if approached by Confed. Despite Gilkarg's mounting success, he lost his son Ratha to Confed pilot Vance Richards, who would one day rise to the rank of Admiral. Ratha ejected, but out of contempt and disgrace he removed his helmet and died in space. Thrakhath became Gilkarg's sole heir as a result of this loss.
Gilkarg's success did not last forever, though. During the year 2639, Confed mounted a counterattack against the McAuliffe occupational forces. A large flight of Raptor Heavy Fighters laid a large array of Porcupine Mines around one of the system's primary jump points, forcing the Kilrathi to back off. The Kilrathi fought off the Raptors when suddenly the mines were remotely detonated. The mines were just a ploy to clear Confed's route into the system, as the entire fleet poured into McAuliffe's skies within moments after the detonation. Within a few hours Gilkarg's fleet and orbital guns were annihilated, forcing the Kilrathi to retreat while the vast majority of the colonists were liberated. Gilkarg ultimately lost McAuliffe, but he was not finished with humanity. Even after his defeat, he continued to formulate plans to claim the ultimate prize: Earth.
During the 2650s, the Kilrathi waged war against humanity in the Vega Sector in what became known as the Vega Campaign. The Terran Confederation ultimately won that battle with the Kilrathi defeat at Venice System in 2654, effectively forcing the Kilrathi to abandon the Sector.
However, Kalralahr Gilkarg was in the Sector at the time and was not ready to surrender. On the Kilrathi colony of Warhammer XII, Gilkarg commissioned the Gravitron Weapon, a device that when launched into a planet's atmosphere increased its gravitational field 137 times, annihilating everything on the surface. Gilkarg attached the weapon to the newly-commissioned KIS Sivar and successfully tested the device on Warhammer XII in order to hide the evidence. The planet was left in ruins, prompting Gilkarg to use the device on the human colonies. In the Epsilon Sector, Gilkarg used the device on the colony of Goddard, destroying it completely and killing 250,000 human colonists. Gilkarg then pulled back the Sivar Fleet to prepare for future attacks on the colonies. Gilkarg had hoped that with the Sivar and its weapon, he could blast his way towards Earth. However, Gilkarg was unprepared for what happened next.
In retaliation for the disaster on Goddard, the Confederation sent the famed TCS Tiger's Claw to intercept the prototype ship and its weapon behind enemy lines in what became known as Operation: Thor's Hammer. They managed to destroy all of its escorts and a Supply Depot. Finally, the ship itself (dubbed "Sivar") was spotted, and the Claw took immediate action against it. Famed human pilot Carl T. LaFong and comrade Joseph Khumalo, and another wing including Christopher Blair tracked down and destroyed the Sivar and the Gravitron Weapon. With the destruction of this ship, Gilkarg's plans came crashing down.
Gilkarg's ambition costed his father an entire strike fleet. These unacceptable failures led to his fatal "accident". He was thrown in chains and was executed by disintegration in 2655 on his father's orders, leaving young Thrakhath to assume leadership and the throne.