A demon whose true name is Anung Un Rama (the Beast of the Apocalypse), Hellboy was brought to Earth as an infant by Nazi occultists. He was discovered by the Allied Forces; amongst them, Professor Trevor Bruttenholm, who formed the United States Bureau for Paranormal Research and Defense (BPRD). In time Hellboy grew to be a large, red-skinned demon with a tail, horns (which he files off, leaving behind the signature circular stumps on his forehead, not to make his appearance more "normal" as some have theorized, but to better pass through doors), cloven hooves for feet, and an oversized right hand made of stone. He has been described as smelling of dry-roasted peanuts. Although a bit gruff, he shows none of the malevolence thought to be intrinsic to demons, and works with other strange creatures in the BPRD. This is said to be because of his upbringing under Professor Bruttenholm, who raised him as a normal boy.
Hellboy fights for the BPRD, an international non-governmental agency, and himself against dark forces including Nazis and Baba Yaga, in a series of tales that have their roots in folklore, pulp magazines, vintage adventure, and horror fiction. In the stories, he is identified as the "World's Greatest Paranormal Investigator."
The comics were adapted into a 2004 film starring Ron Perlman, a 2008 film sequel, Hellboy II: The Golden Army, and two straight-to-DVD animated films, Hellboy: Sword of Storms and Hellboy: Blood and Iron.