Kil-Lor was a Kryptonian terrorist active on the planet Krypton many years before the birth of Superman. Kil-Lor sought to destroy the capital city's democratic government, and took aims to completely conquer the planet. Jax-Tor, director of the Kryptonian Bureau of Investigation sent agents Jor-El and Lara Lor-Van undercover to infiltrate Kil-Lor's operation and gather as much incriminating evidence against him as possible.
On the day that the two agents were brought into Kil-Lor's confidence, Jor-El and Lara's future son, Superman, arrived in their timeline from many years in the future. He witnessed his parents conspiring with Kil-Lor and mistakenly believed that they were actually traitors to Krypton.
K.B.I. agents raided Kil-Lor's lab arresting all three. Jor-El informed the officers that he was actually an undercover agent, but was unable to convince them of his identity. Director Jax-Tor passed away that very morning, and he was the only agent who could confirm their assignments. Kil-Lor, Jor-El and Lara were placed inside of a prison satellite – a device designed to alter their behavior patterns, transforming them into good, law-abiding citizens. The K.B.I. launched the satellite into outer space, but Superman secretly followed the ship's trajectory.
Landing on a small asteroid in a yellow star system, Kil-Lor emerged from the prison satellite only to discover that he now possessed powers similar to that of Superman. He openly declared his intention to conquer Krypton, unaware that his powers would disappear once he entered a star system with a red sun. Regardless, Superman felt obligated to stop him and the two fought on the surface of the asteroid. Kil-Lor quickly adapted to the use of his powers and was Superman's equal in every way. In the midst of battle, Superman flew off to check on Jor-El and Lara.
Knowing that Kil-Lor would be observing him with x-ray vision, he told his parents that Kil-Lor could in fact conceivably destroy Krypton by smashing large pieces of matter together at super-speed, creating a nuclear explosion.
Kil-Lor (using super-hearing), overheard him and experimented with the idea by smashing two large pieces of asteroid together. However, rather than creating a nuclear explosion as he had hoped, the colliding material instead created a chain reaction, transforming the immediate area into deadly Kryptonite. Kil-Lor lost all of his super powers and fell down unconscious. Kil-Lor's final fate remains unknown.
- Kryptonian Physiology: Under the effects of a "yellow" sun, Kil-Lor possesses the same potential powers as an average Kryptonian. These include:
- Solar Energy Absorption: Under optimal conditions, this is the main source of Kil-Lor's super powers as they are contingent upon exposure to solar radiation from a yellow sun star system. His biological make up includes a number of organs which lack analogues in humans and whose functions are unknown. It is believed that between one or more of these and his bio-cellular matrix, "yellow" solar energy is stored for later use. This allows for the use of these powers to fade when yellow solar radiation is not available instead of immediate failure.
- Heat Vision: Kil-Lor can, as a conscious act, fire beams of intense heat at a target by looking at it. He can vary the heat and area affected.
- Super-Hearing: Kil-Lor's hearing is sensitive enough to hear any sound at any volume or pitch. With skill and concentration, he can block out ambient sounds to focus on a specific source or frequency.
- Enhanced Vision: Kil-Lor's vision processes the entire electromagnetic spectrum as well as allowing vast control over selective perception and focus.
This umbrella ability includes the following:
- Electromagnetic Spectrum Vision: Kil-Lor can see well into most of the electromagnetic spectrum. He can see and identify radio and television signals as well as all other broadcast or transmitted frequencies. Using this ability, he can avoid detection by radar or satellite monitoring methods. This also allows him to see the aura generated by living thing.
- Telescopic Vision: This is the ability to see something at a great distance, without violating the laws of physics. Though limited, the exact extent of the ability is undetermined. In function, it is similar to the zoom lens on a camera.
- X-Ray Vision: This is the ability to see through any volume of matter except lead. Kil-Lors can see things behind a solid, opaque object as if it were not there. He can focus this ability to "peel back" layers of an object, allowing hidden image or inner workings to be observed. The exact type of energy perceived—such as x-rays, cosmic rays, or some other energy invisible to normal humans—is unclear. This ability perceives an ambient energy source though, it does not involve the eye projecting a concentrated, possibly toxic, beam to be reflected back from objects.
- Microscopic Vision: This is the ability to see extremely small objects and images down to the atomic level.
- Infrared Vision: Kil-Lor can see with better acuity in darkness, and to a degree in total darkness.
- Flight: Kil-Lor is able to manipulate graviton particles to defy the forces of gravity and achieve flight. This ranges from hovering to moving in any posture, in any direction.
- Invulnerability: Due to the interaction of his dense molecular structure and supercharged bio-electric aura, Kil-Lor is nigh-invulnerable to extreme energy forces. In addition, his extends this protection against toxins and diseases.
- Superhuman Stamina: Kil-Lor is able to maintain continuous strenuous physical action for an indefinite period of time. This based on his body converting yellow solar radiation directly to energy, but is limited by physiological and psychological needs to eat, drink, and sleep.
- Superhuman Strength: Kil-Lor's strength is augmented by yellow solar radiation interacting with the greater than human density, resilience and biological efficiency of his musculature. His strength is more an act of conscious will on energy fields than actual physical strength. It is this act of conscious will that enables him to perform physical feats that are beyond the mere application force, such as moving a mountain top without said rock crumbling under its own mass.
- Superhuman Speed: Kil-Lor is able to move at incredible speed by sheer force of will. This extends to his perceptions and allows for feats such as catching bullets in mid flight as well as covering vast distances in little or no time.
This also confers:
- Super-Breath: Kil-Lor is able to create hurricane force winds by exhaling air from his lungs. He can chill the air as it leaves his lungs to freeze targets. He can also reverse the process to pull large volumes of air or vapor into his lungs.
- Kryptonian Physiology: Under the effects of a "yellow" sun, Kil-Lor possesses the same potential weaknesses as an average Kryptonian. These include:
- This version of Kil-Lor, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- Kil-Lor's final fate is a matter of speculation. To all accounts, he appears to have died from the effects of Kryptonite poisoning, but it is difficult to believe that Superman would allow a defenseless man to die, no matter how evil he is. If he did not die on the asteroid, he may have passed away of natural causes some time later, or he may have died during the destruction of Krypton. There is a remote chance that Kil-Lor may have been one of the surviving Kryptonians found in either Kandor or Argo City.
- 4 Appearances of Kil-Lor (Earth-One)
- 1 Images featuring Kil-Lor (Earth-One)
- Quotations by or about Kil-Lor (Earth-One)
- Character Gallery: Kil-Lor (Earth-One)