Post-Flashpoint

In the New 52, Belial was able to overthrow Lucifer to become King of Hell. Belial attempted to create a dimensional tear between Hell and Earth, but was eventually killed by Etrigan, along with his brothers Ruskoff and Suge.

Pre-Flashpoint

One of the most ambitious demons in hell, he aspires to rule Hell as one of its Triumvirate. He is the father of the demon Etrigan (Demon), the wizard Merlin, and Lord Scapegoat; a demon of Hell. He and his children have often been at ends with each other, due to his schemes conflicting with those of there own, their fights are legendary. Rarely does he appear on Earth, though when he has, his schemes are usually thwarted. One of Belial's appearances on Earth was when he first encountered Arak, Son Of Thunder. He prefers to work behind the scenes, lending his demonic powers, as one of the six demons, to empower Sabbac (a blasphemous parody of Captain Marvel).

Ultimately his skills and ambition granted him the position as head of the Dominus Nerons secret police, and as such one of the most influential and politically powerful demons in Hell before Neron was removed from power by Lord Satanus and Lady Blaze, where he like many other demons (presumably) fell victim to Satanus' secret weapon that turned them into humans.