Within a year of his employment Horror managed to destroy the city's drug trade and eliminate all of Zampa's competitors, earning both a reputation as a top-notch enforcer and the ire of the Pacific City Police Department. Although he appears human, Doc Horror is actually a native of a parallel world referred to only as the "Black Planet" that was overrun by the nefarious Crim following a great global war. Horror used his scientific genius to develop a technology that could open interdimensional gateways to other worlds in an effort to banish the Crim forever; however, Horror was betrayed by his government as part of their surrender and handed over to the traitor and Crim conspirator named Fane. Horror revealed the secrets of his technology under threat of Eve's life, but managed to push Eve into the open gateway and sending her here to Earth. After a struggle with Fane, Horror went through the gateway as well, apparently escaping his hellish world and leaving the Crim behind forever.

Once on Earth, Horror used his knowledge of advanced technology and the occult to gather resources to find Eve, traveling the world, earning the loyalty of fellow paranormal outcasts, and eventually falling in with the Zampa crime family. Don Lupo's resources located the young Eve and reunited her with her father, allowing them and their new friends to make a new home for themselves here in their new world.

Horror requires regular treatments with a special medicine he developed to control "a rather nasty virus" he picked up on one of his expeditions. The nature of this disease is uncertain, as Horror will only say that if left untreated he would "hurt a lot of people," but an unused story panel found in the artist's notes in the back of the Black Planet compilation indicates that Horror is in fact a lycanthrope.

Doc Horror's preferred weapons are dual .45 caliber automatic pistols, which can be equipped with different types of ammunition that he himself creates. In the final issue of the Black Planet story arc, Doc Horror uses magic bullets that can send pieces of the target into other dimensions for a truly devastating effect. Aside from firearms, Horror carries a vast knowledge of arcane magic and advanced technology that aid him against supernatural enemies. Horror also appears to have a much stronger constitution than normal humans, taking bullets "like they were bee stings," and has no problem going toe-to-toe with vicious monsters and demons.