Vertigo/N

Nergal
Nergal is a powerful demon from Hell. Back in the late 1970s, a terror elemental known as the Norfulthing appeared in Newcastle, England to protect a young girl named Astra Logue, who had become the victim of tantric sex rituals. The Norfulthing slaughtered everyone in the area. A group of amateur occultists, led by John Constantine attempted to banish the Norfulthing. To accomplish this, John summoned Nergal in the hopes that the more powerful entity would destroy the terror elemental. Nergal accomplished this, but in so doing, decided to avail himself of Astra as well. He took possession of Astra, and John and friends were now tasked with exorcising him from the girl's body. This attempt failed horribly, and Nergal took Astra's soul to Hell. This botched exorcism became one of the defining moments in John Constantine's career.

Norfulthing
The Norfulthing is a terror elemental that manifests itself into a physical form based upon the subconscious creativity of another. The Norfulthing is not a traditional demon in that it is not bound by common restrictions associated with invocation or summoning. It has once been described as partly a giant dog and partly a monkey "with a purple bum, like at the zoo". The Norfulthing wears its internal organs on the outside of its skin, including its heart, muscles, veins and genitalia. In 1978, amateur occultist and nightclub owner Alex Logue held a series of tantric sex rituals in the cellar of his establishment, the Casanova Club. He forced his young daughter Astra to partake in these rituals, and the experience traumatized her so greatly, that she inadvertently conjured up the terror elemental to protect her. The Norfulthing slaughtered everyone in room, sparing only Astra. A short time later, John Constantine and a group of his friends (informally known as the Newcastle Crew), discovered the carnage in the bottom of Logue's basement. In an effort to destroy the Norfulthing, John attempted to summon a more powerful demon to combat it. He mis-spoke the spell, and summoned the demon Nergal, who took possession of Astra Logue and used her as the instrument by which to destroy the Norfulthing.

Nybbas
Nybbas was a demon from Hell. He assumed a quasi-humanoid form with a bald head, pointed ears, a circular marking upon his brow. He tended to wear clothing similar to that worn by 15th century privateers. Like many demons, he was responsible for collecting souls and sending them to the Plains of Erebus. The most sought-after soul in his conquest was that of John Constantine. He encountered Constantine in London, many years ago, and was prepared to kill him. However, John always had a trick up his sleeve and bonded himself to the demon, knowing that he too would be taken to Erebus where he would then suffer the rage of all the souls he consigned there. Though Nybbas had to spare his life, he did leave one lasting legacy. He placed a curse on John Constantine, infecting him with a viral plague. John called upon the aid of an old contact named Mercury. Mercury knew the demon's true name and was able to banish him. John conducted a ritual to heal himself.