Verminus Rex was thought to be the last member of a race rat-people, known as the Berev'ha Dentii. It is unknown how the other members of his race had perished. At some point in his history he was considered to be Prince of the Short Teeth race. During World War on the battle fields of Germany, Verminus clashed with the Ghost Rider. He eventually lost his life by stepping onto a landmine. However, this would not be the end of the hellish rodent-man. He would be resurrected by Mephisto's prodigal son Blackheart to serve as one of his new Spirits of Vengeance.
After his incarnation Ghost Rider (Daniel Ketch) discovered Verminus in a campaign of abducting and consuming helpless human beings. Daniel incinerated Verminus in a blast of hellfire causing his second death, The fiendish rodent was resurrected once again by Blackheart. Verminus and his undead counter parts, Wallow, Pao Fu and Doghead were able to snatch the heart out of the chest of the Ghost Rider. Blackheart offered Ghost Rider the opportunity to lead his new Spirits of Vengeance, he quickly refused, although he considered being transformed into his original form of Nobel Kale, thus breaking the curse that had plagued his descendants for centuries. Ghost Rider tried to convince the Spirits that Blackheart was only using them, Verminus told him that Blackheart had given him what he most wanted and needed, respect and vengeance. He then stood by as Ghost Rider accepted, on the condition that he be allowed to marry Pao Fu and Black Rose, and witnessed the rebirth of Ghost Rider as Noble Kale.
Sometime later, Rex was stabbed with the blade made from the demon Zarathos' rib. The blade was intended to be used by Black Rose to slay Kale. Rex survived the attack to witness Ghost Rider, strengthened with the full memories of Noble Kale who ultimately overthrew Blackheart, becoming the ruler of Blackheart's Hell and giving its inhabitants freedom, but he soon departed for Earth, leaving Vengeance (Michale Badilino) in charge and the Spirits of Vengeance as acting governors to police the realm as they saw fit so long as they followed the only law, that they must do no more evil. Like the equally corrupt Wallow, Rex was disgusted with Kale's law.
Verminus Rex was later contacted by Zadkiel, a rouge angel plotting to conquer Heaven. Zadkiel offered to restore the Berev'ha Dentii race and give Rex a new corporeal form. To receive Zadkiel's gift, Rex had to convince Ketch to become a lieutenant in Zadkiel's service. Agreeing, Rex was empowered with the Spirit of Vengeance's essence, allowing him to siphon the power of the other Ghost Riders. Rex and the Berev'ha Dentii hunted and preyed upon various Ghost Riders, luring Ketch into siphoning the Ghost Riders' essences from Rex's body, overloading Ketch and tricking him into giving up his soul. However, after Zadkiel's agent Mister Eleven refused to give Rex a new body, Rex demanded to see Zadkiel and attacked Mister Eleven, who sent Rex's soul to hell.