Hellboy is a creature summoned or perhaps born in the final months of World War II by the historical figure Grigori Rasputin on Tarmagant Island, off the coast of Scotland, having been commissioned by the Nazis to change the tide of war ("Project Ragna Rok"). He appears in a fireball in a ruined church in East Bromwich, England, on December 23, 1944. Proving not to be a devil, but a young, devil-like creature with red skin, horns, a tail, and a large stone right hand, he is dubbed "Hellboy" by Professor Trevor Bruttenholm.
Taken by the United States armed forces to an Air Force base in New Mexico, Hellboy is raised by the United States Army and by the Bureau for Paranormal Research and Defense (BPRD), a federal agency dedicated to combating occult threats.
As an adult, Hellboy becomes the primary agent for the BPRD, alongside other human and quasi-human agents that include Kate Corrigan, a professor of folklore at New York University; Abe Sapien, an amphibian humanoid (Ichthyo sapien); Liz Sherman, a young pyrokinetic; Roger, an unusually large homunculus; Johann Krauss, the spirit of a medium kept in a containment suit; and Captain Ben Daimio, a special operations man with occult experiences, the latter two of which have not met Hellboy due to Hellboy's resignation from the Bureau.
During a visit to Bromwich Church (the place of his "birth"), Hellboy learns he had been conceived 300 years ago by a witch, Catherine Tanner-Tremaine, and a demon Prince of Sheol. At this time, Hellboy had not existed as a baby in the "real" world; the prince's "favorite son" was considered to be "a power waiting to be born." Hellboy's "mother" also had children: a nun and a priest who would later haunt the church, dying in an attempt to stop the demon from claiming Tanner-Tremaine on her deathbed.
Hellboy is regarded as a minor celebrity, having been granted "honorary human" status by the United Nations in 1952, and is known as the "world's greatest paranormal investigator". As such, he interacts regularly with humans, primarily law enforcement officials, the military, and various "scholars of the weird", most of whom are not presented as overtly reacting to his strange appearance. Conversely, the film adaptations depict Hellboy living at the BPRD with limited access to the outside world, and considered simply an urban legend by the general populace.