In the distant past, King Zarkon of Daibazaal ruled over the Galra people and held an alliance with King Alfor of Altea as well as fellow warrior leaders Gyrgan, Trigel, and Blaytz. One fateful day, a comet crashed into Daibazaal's surface, causing a rift between realities because of the comet's unique properties. This led Altean alchemists to investigate the site, and thus Zarkon met Honerva, eventually marrying her. With the comet's substance, Alfor created the Voltron Lions and made Zarkon the leader and head of the original Paladins, first using Voltron to combat the darkness that attacked from the other side of the rift. Soon Voltron became known as a heroic fighting force and Coran's grandfather built the Castle of Lions to house the Lions.

Once Zarkon and his wife became obsessed with the Quintessence found in the reality rift, the exposure damaging Honerva's health, Zarkon attempted to bring Honerva into the rift using Voltron so he could save her with the Quintessence and darkness within. His fellow Paladins were not aware of his trickery until it was too late. The overexposure seemed to kill both he and his wife when they recklessly left the safety of Voltron inside the rift.

But after Alfor held their funeral and destroyed the evacuated Daibazaal to erase the reality rift forever, Zarkon and Honerva awakened, changed and corrupted by their ordeal. Zarkon flew into a rage at Alfor and the Alteans for the loss of the rift, sparking a war and the beginnings of the Galra Empire. Zarkon desired to capture Voltron so he could use the robot's power to create another rift and obtain the purest Quintessence of infinite amount.[1] This led King Alfor to put Allura and Coran in a deep sleep inside cryo-pods within the Castle of Lions, and to scatter the Voltron Lions to hidden locations across the universe so they would not fall into Zarkon's hands. Alfor led Zarkon to believe the Lions were destroyed, and so Zarkon slayed the king, his fellow Paladins, and destroyed Altea.

Zarkon began expanding his military power throughout the known universe, until his kingdom became the Galra Empire that ruled over all people. At his side was his advisor and former wife, Honerva, who had become the witch Haggar; he trained Sendak personally and the commander became his first in command. Although Zarkon believed the Lions were destroyed, the Empire was able to locate the Red Lion at some point in time and it was kept on Sendak's ship as Zarkon searched the universe for the remaining Lions.

After nearly ten thousand years had passed, the unnamed Galra Commander was scouting Earth's solar system and happened upon Shiro, Samuel Holt, and Matthew Holt on Kerberos. Zarkon ordered them taken to Haggar's Druids for interrogation. Afterward, he watched Shiro battle Myzax in the Empire's arena for his own entertainment.

Prior to Voltron's return, it is known that Zarkon had a son, Lotor, who became exiled, but the prince's time of birth, and circumstances of exile are unknown.

Season One

Season Two

Season Three

While Lotor takes over leading the Galra Empire, Zarkon remains at in a comatose state because of his battle with Voltron until Haggar manages to awaken him with her dark magic.

Cite error: <ref> tags exist, but no <references/> tag was found