Lord Satanus resembled a traditional demon, save that he wore a heavy Roman-style helmet, and either had black skin or the helmet buried his face in shadow. The Demon War storyline reintroduced him as Blaze's brother. They fought for possession of Blaze's domain, using Superman as a pawn. At the end of the story it was revealed that Satanus was disguised as Colin Thornton, the publisher of Newstime magazine, who first appeared in Nov. 1989, and had previously hired Clark Kent as editor.
Lord Satanus, meanwhile, had created DMN, a magical drug that transformed people into demons, which he arranged to be sent to areas of the world where people were in desperate straits. After the Fall of Metropolis, the city became one of these areas. Horrified by what had befallen his home, Satanus sent a disguised magical message to Zatanna, who used Perry White and Superman's knowledge of the city to restore it. Satanus would use the DMN addicts again, however, to distract Shazam from detecting his presence when the wizard visited Metropolis.
Following Brainiac-13's recreation of Metropolis, Satanus made an ambitious effort to capture the soul of the entire city. Superman offered his own soul in exchange, but eventually thwarted Satanus with the help of a young psychic and a mysterious shaman named Night Eagle who, it was implied, might be Blaze.
In another appearance, Lord Satanus appeared in the Reign of Emperor Joker arc of the Superman titles. In this appearance, he dwelled in that reality's Hell (a literal flaming place accommodated to include annoying songs) and offered the angelic Supergirl and the somewhat-brainwashed Superboy their heart's desires in exchange for their souls, much like his fellow demon Neron, after they had been killed by a blast fired by the monstrous Ignition. He commented that, much like God, he was forced to live in all realities and dimensions simultaneously. At the end, when Supergirl annoyed him with her incessant prayer, he shunted them to life, commenting there were not many Hells he could send them that were worse than the Joker's world.
Satanus recently revealed to Superman that he was Colin Thornton when the Spectre arrived in Metropolis, as part of his mission to destroy all evil magic. Whether Lord Satanus was destroyed or not was not revealed. He does appear at the magician's seance to summon the Spectre during Infinite Crisis. He is later found to have survived.
Lord Satanus, along with his younger sister Blaze, has managed to become the ruler of Purgatory, and is leading a rebellion in hell by offering "Hope for the hopeless". They preach to the damned about the hope of getting beyond being a simple realm of suffering eternally and becoming a place to atone for past sins and then to be free of of torment for the debts long since paid. Satanus preaches of a hell not bound by laws handed down long ago, stating that the only ones keeping the laws in place are those who continue to toil under them without hope. He pledges to change this.
Neron is using all of his power to oppose him, the conflict has recently drawn all magic wielding heroes down to hell as they are recruited to fight for one side or the other.
Lord Satanus led his forces against those of Neron in a battle that raged throughout the Infernal Dominion, throwing Hell into chaos the likes of which it has not known for Centuries. While at first his forces were holding their own, as time went by, the overwhelming number of warriors and Demons under Neron's command became to much for his forces to handle. While his sister Blaze faced off against the sorcerer Doctor Fate, Satanus set the last of his plans in motion.
Coming to his sister after the end of her duel with Fate, Satanus revealed the truth of his plans to her. Reminding her of the magical drug he had created years ago, DMN, he reminded her of it's properties for turning Mortal's to Demons. It could also turn Demon's into Humans, he explained that the entire war had been a ruse, a way for his plague-carrying troops to reach throughout Hell, spreading his plague. He also simultaneously used his power to create a conjuring for Neron to witness their conversation, a direct challenge to his power.
Neron accepted, and broadcasting his intentions to the entirety of the Infernal Dominion, teleported to Satanus to bring him to task for his actions. Satanus fought Neron in a magical duel that spread across the realm of Hell. Satanus was able to barely stand against Neron, and just as his enemy prepared to end their fight, he triggered his trap, speaking aloud "Shazam". All the Demon's infected with DMN were transformed to human's, and each one drew power form Neron, reverting him back to the pitiful Demon he had started out as.
Lord Satanus wasted no time beheading Neron. Proclaiming himself ruler of Hell, he gifted his sister with the head of their enemy, and prepared for his rule to begin.
Transporting to Neron's former Citadel, Lord Satanus and his sister Lady Blaze move in, taking over. Trading in his battle armor for robes, Satanus is waited on by numerous servants. Waiting for the Infernal Dominion to re-align itself to his will as it had for Neron, Satanus cut it off from all other planes while his power was consolidated.
He explained to his sister Blaze that instead of placing demons over the souls of the Damned to watch and torment them, he would instead allow them to torment each other. He explained that needing to pass blame on to others, because of their curse of Pride they would keep each other in check, blaming one another for their failures in life and damning themselves even further. Entering his throne room, where thrones waited for both him and his sister, he picked up the dispatched head of Neron, and forced it to say the words that would hand over control to him.
He then used his power to re-constitute one of his former demonic servants, sending him forth to find Dr. Fate so that he could be properly punished for the disfigurement of his sister. Waiting as his power grew, Satanus used a burst of strength to remodel and reshape the Citadel. Sitting on his throne he began to plan, ready to bring all past debts in to call. At the end of Reign in Hell, Satanus in a moment of weakness in replaced as Leader of Hell by his sister, Lady Blaze. Blaze then casts Satanus into the Abyss.
Later Satanus teleports the JLA to Hell to unwittingly get him the nine pieces of the Hell Mask so that he might escape his sister's imprisonment. The JLA gets the pieces he assembles the mask but the heroes destroy it again and he is left to be punished by Lady Blaze for his trickery.