Bifrons is a demon, who served as a major antagonist Abe Sapien: A Darkness so Great and supporting antagonist B.P.R.D.: The Devil You Know— Pandemonium., comics within Mike Mignola's Hellboy-universe.
Bifrons was at some point trapped in a bottle as a familiar spirit, until Arbogast, a priest, got. Due to this Bifrons was spared from the slaughter of most infernal nobles when Hellboy arrived in Hell. The priest, who witnessed the arrival of the Ogdru Hem and the destruction they caused, hoped to use the demon and it's power to cause the Christian rapture. He would eventually get free after Arbogast was killed by Abe Sapien and thudded dropped and broke the bottle that contained the demon.
Bifrons' arrval causes rain to fall and the demon turn to Abe Sapien and group of human-survivors. He attacks them by spitting fire, and comments how the end of the world is much different that of biblical prophecies, even stating how God has abandoned them. He would start to battle Dayana, a follower of Santa Muerte, who managed to defeat the demon and scatted him into the air.
He, alongside Balam, was later summoned by Yomyael (while possessing Varvara) who sought to rebuild Pandemonium on Earth. The three of them were the last leaders from original Court of the Fly (the most high-ranking demons), and Yomyael hoped to make Earth their new home, and re-enslave the lesser devils of the Hell.
Bifrons was at first skeptical of Yomyael, who had stolen the ring of now dead Duke of Hell Amdusias. Bifrons had gotten his own ring from the late Prince of Hell Beelzebub. Yomyael reminded the Earl that she controls him and Balam through the same blade that Hellboy had used to kill Satan.
Bifrons later led an aerial assault against the forces of the B.P.R.D. who seeked to wipe out the remaining demons in New York. The Earl notably battled with Liz Sherman, being impressed with power of the veil she had mastered, and was eventually killed by her. His body was quickly seen in the waters surrounding New York when the B.P.R.D. escaped a reborn Rasputin, who reawakened the Ogdru Hem and served as the herald for the Ogdru Jahad.