Lucifer hails from an alien race of conquerors from the planet Quist, although their empire is known as the Arcane. His race would methodically seize control of other worlds using a master machine known as Dominus. This building-sized transmitter produced rays of will-deadening energy, forcing populations to submit to the rule of the Arcane. Because each species was unique, Dominus had to be adjusted, fine-tuned and tested by an advance scout before full conquest of a world began. On Earth, this was the task of Agent One of the Arcane, who concealed his identity behind the mask of "Lucifer." [X-Men (1st series) #21]
Years ago, Lucifer formulated a testing ground within a small, walled city in Tibet. In this isolated environment, Lucifer established a transmitter that seized the willpower of select people within the city. These agents helped him to dominate the rest of the populace, and Lucifer became a tyrant who held an iron rule over the people of the city. One day, the wandering mutant telepath Charles Xavier detected something amiss as he neared the walled city. Once inside, he learned of the fearsome ruler that subjugated the people. Xavier rallied a local resistance group and used his powers to help them infiltrate Lucifer's castle.
The Supreme One of the Arcane registered the damage to Lucifer's systems by Xavier. He cautioned Agent One to abandon "Site A" with the data Dominus needed to adjust itself and control humanity. Lucifer obeyed orders but, when he was confronted by Xavier while escaping, Lucifer triggered a defense mechanism and dropped a massive stone block on the telepath. Xavier survived, but his legs were crushed in the attack, leaving him unable to walk. [X-Men (1st series) #20]
Lucifer left his crippled foe to his fate, moving on to "Site B," concealed in Buchanan's Butte in the southwest desert of Arizona. It was there that Dominus was transported using ionic teleportation technology, along with the control robots necessary for operating Dominus once it came online. Lucifer spent the next ten years monitoring Dominus as it adapted to the human brain wave patterns he fed into it, preparing for worldwide domination.
Lucifer carried out additional schemes as he waited. In the Balkans, he prepared a thermal bomb which would be transported through Earth's mantle to destroy Antarctica. The resulting tidal waves and mountains of ice would destabilize the planet, leaving it primed for take over. By this point, the wheelchair-bound Charles Xavier had re-established himself as Professor X of the X-Men. He detected Lucifer's schemes and summoned his X-Men to the Balkans to confront the alien. Xavier was caught off-guard when Lucifer revealed the detonator of the thermal bomb was linked to his heartbeat, meaning Lucifer could not be physically harmed or else the bomb would explode. Unfortunately, the Avengers had also detected the threat of Lucifer and come to Europe. Xavier was forced to pit his X-Men against the Avengers to stall them until he found a way to knock Lucifer out without slowing his heartbeat. Fortunately, he was successful and Cyclops disabled the fuse of the thermal bomb, ending this plot of Lucifer's. [X-Men (1st series) #9]
Nevertheless, Lucifer's plans continued and, as they neared completion, he tested Dominus' ability to influence people at range. To kill two birds with one stone, he used Dominus to implant a thought in the minds of Blob and Unus, two former foes of the X-Men, convincing them to team up and pose as X-Men while committing robberies, drawing out their common foes. Lucifer was unsuccessful in getting Xavier out in the open, but he did succeed in getting the professor to search the globe for him telepathically. This was enough, and Lucifer used Dominus to transmit a paralyzing mental ray back down Xavier's own telepathic probe, leaving him near death. Xavier only survived by force of will and directing his X-Men to construct a beam distorter that blocked Dominus’ ray. [X-Men (1st series) #20]
The X-Men tracked Lucifer to Buchanan's Butte and forced their way into his stronghold. As a gloating Lucifer explained the secrets of the Arcane to a captive Xavier, however, Professor X realized the flaw in Dominus’ design. Dominus itself was practically invincible, designed to absorb and return force at its attackers as a protective measure. The Ultra-Robots who operated Dominus were not indestructible, though. Xavier subliminally compelled Lucifer to direct the robots into battle with the X-Men, placing them in harm's way. Sure enough, the X-Men were able to divert Dominus’ own defenses against the Ultra-Robots by luring them into striking the super-computer, destroying the irreplaceable robots. Not only was Dominus now useless against the Earth, but the Supreme One of the Arcane chastised Lucifer for his poor display, banishing him to the Nameless Dimension as punishment for his failure. [X-Men (1st series) #21]
In the Nameless Dimension, Lucifer spent years cultivating ionic power to strengthen himself, as well as scrounging the parts to build a dimensional transmitter. This transmitter enabled him to cross the barrier between dimensions back to Earth, but it was only successful for a short period of time, allowing him to materialize within a limited radius. Seeking an agent, Lucifer mentally drew a passing security guard named Charlie Gray into the abandoned lot to which his transmitter brought him. Lucifer preyed upon Gray's insecurities, offering him power in exchange for his services. Charlie Gray became Lucifer's host on Earth, with the two of them cohabitating Gray's body, now filled with Lucifer's ionic power and capable of traveling outside the radius determined by the dimensional transmitter.
Lucifer hoped Gray's employer Tony Stark could construct a second dimensional transmitter on Earth's side of the barrier, allowing Lucifer to cross over from the Nameless Dimension permanently. Charlie Gray, under Lucifer's direction, attacked Stark Industries to draw out its founder. Gray reveled in being powerful, but Lucifer cautioned him that the alien's ionic power was finite, and should not be wasted needlessly. As Lucifer, Gray tore into Iron Man as he tried to locate Tony Stark. However, Gray's wife Wilma had recognized Charlie on his rampage, and stepped forward to stop him from causing any more chaos. Lucifer bade Charlie to smash through the useless woman, but Charlie Gray's love for his wife caused him to cast off the power Lucifer had granted him. Gray returned to normal and Lucifer's essence returned to the Nameless Dimension unfulfilled. [Iron Man (1st series) #20]
Years passed before Lucifer acquired some “casadrax mineral” to improve the dimensional transmitter from his side of the barrier. He was satisfactorily able to beam entirely to the Earth dimension. However, the process proved to be unstable and he soon found himself being drawn back into the Nameless Dimension. Lucifer had stumbled into a burglary in Harlem when he appeared, and used it as an opportunity to claim a new host. The thug Rafe Michel was forcibly assimilated by Lucifer, allowing him to fully control their combined form instead of merely guiding his host as he did with Charlie Gray. Lucifer had an encounter with the Falcon before fleeing in Michel's body.
He discovered that this possession put too much of a strain on Michel's human physiology, with the ionic energy burning him up from the inside. Consequently, Lucifer sought a second host and found the Zodiac Cartel chief Grover Raymond, a.k.a. Aries, in a nearby police station. Lucifer assimilated Aries as well, splitting his power and his consciousness between Aries and Michel's bodies. In this diluted state, Lucifer's essence no longer gave his hosts ionic projecting powers, although they still retained his ionic strength. With Michel-Lucifer still weak from before, Aries-Lucifer emerged as the dominant of the two Lucifers, despite them sharing the same mind. He arranged an alliance with Boss Morgan, a Harlem crime boss, against their mutual foe the Falcon. The Luci also returned to Buchanan's Butte to retrieve several Ultra-Robots that were not destroyed in the fight with the X-Men.
Back in Harlem, the two Lucifers and the Ultra-Robots fought against Falcon and a civilian Steve Rogers, who used a trash can lid in place of his famous shield. Rogers also discovered the Ultra Robots were vulnerable to each other and maneuvered them into destroying one another. The Luci struck back against Rogers and the Falcon, only for Michel-Lucifer to collapse. They learned that possessing Aries had not saved the first host from Lucifer's ionic energy. Michel-Lucifer died of the strain placed on his body and, due to their link, the Aries-Lucifer passed on moments later despite being in relative health. Rafe Michel and Grover Raymond were dead, and Lucifer re-coalesced back in the Nameless Dimension, out of casadrax and unable to return to the Earth dimension. [Captain America & the Falcon (1st series) #177-178]
Lucifer's constant attention-drawing failures brought forth the ire of the Arcane, especially Dominus itself. The master machine had finally become advanced enough to develop sentience and enslave the Quist themselves. Seeking to re-establish its plans for a covert overthrow of Earth, Dominus reportedly had Lucifer terminated in the Nameless Dimension. [West Coast Avengers (2nd series) #24] Dominus then took possession of a human host for itself and re-engineered its base in Buchanan's Butte. His new minions Sunstroke, Butte, Gila and Cactus monitored the southwest for potential intervention by super-heroes, but in doing so inadvertently drew the attention of the West Coast Avengers.
Once they infiltrated his base, Dominus attempted to use the dominator effect to subdue the Avengers' minds. He didn't account for the multiple personalities of Moon Knight, however, who remained defiant despite two blasts. This resistance did not compute, and Dominus drove itself mad trying to explain the failure in its systems. The main Dominus super-computer blasted out into space, fleeing Earth instead of making further attempts at conquest. [West Coast Avengers (2nd series) #17-24] The Arcane left behind a doomsday mech known as Dominex which activated several years later. Dominex was programmed to self-detonate at the [Murray Fracture Zone], tearing the planet apart. It was stopped by the Avengers and the Thunderbolts. [Avengers (3rd series) #12]
[Note: According to X-Men: Declassified #1, the entity known as Onslaught was not the tertiary mind created from the merger of Xavier and Magneto. Instead, it was a parasitic psi-mind cast by Lucifer into Xavier's subconscious when they fought in the Balkans. X-Men: Declassified was filled with dubious revelations, purportedly manufactured by Bastion to undermine the X-Men, and should not be taken as gospel.]
Lucifer's ionic energy was apparently the same as that utilized by Wonder Man, Atlas and Count Nefaria. The residual ionic energy left on Charlie Gray and the deceased hosts Grover "Aries" Raymond and Rafe Michel was siphoned by Nefaria in order to restore his own ionic powers. [Iron Man Annual '99] Ionic individuals often demonstrate immortality, and perhaps this is how Lucifer survived being "terminated" as Dominus put it. Many years later, Lucifer resurfaced on Earth intent to pursue his own plans of conquest. Lucifer had learned how to use his psychic powers in new ways during his absence. He could now partially or fully assume control of others, bringing them into a parasitic hive mind where each body acted as an agreeable extension of his overall will.
Seeking a launching point for his new "cult of personality," Lucifer possessed a man named Heylel in the town of Lago, New York. People of strong emotions, full of hate and fear, were more susceptible to Lucifer's control and Lago was infamous for its bigotry after taking only minutes to acquit a mob of murdering a mutant in the streets. As he slowly assimilated the minds of Lago into his psychic hive, the town's population became more openly accepting of others under Lucifer's influence. Charles Xavier, recently resurrected in a new incarnation known as X, began investigating this sudden change in the people of Lago. Although he detected Lucifer's involvement, he invited the surviving original X-Men (Jean Grey, Iceman, Beast and Archangel) to join him in Lago without letting on to them what he had discovered.
During their stay in Lago, Beast was captured and assimilated by Lucifer. X and the others tracked him down and confronted the ionically-powered Heylel and Lucifer's dozens of assimilated townspeople. X and Jean Grey worked to separate Beast from the hive mind and succeeded due to the fact he was only recently inducted into it. As Lucifer attempted to assimilate Angel, the X-Man's second personality Archangel surfaced and decapitated Heylel with a swipe of his metallic wings. Although Beast survived, the other townspeople all died as a result of the psychic backlash through their connection to Lucifer.
Past events make it possible that the death of Heylel does not mean Lucifer died as well. The Arcane alien may one day resurface to plague Xavier and the X-Men again. [Astonishing X-Men (4th series) Annual #1]