Fictional character biography
The being is outside of the Presence's creation. It is the soul of darkness itself, a complete absence of divine light. In every way equal to the power of the Presence, it is his opposite who existed before Creation.
After the Crisis on Infinite Earths, a group of mystic madmen of the Brujería cult attempted to conduct a mystic ritual to contact the Great Evil Beast; it went awry and instead the entity awoke as a furious monster, unknowing of its own power and confused about its existence.
It encountered a number of mystical heroes (Etrigan, Doctor Fate, the Spectre), who unwittingly angered the being and directed it against Heaven, leaving the defeated heroes behind. They did this unknowingly, despite their best intentions; Etrigan taught it that darkness was evil, Dr. Fate told him that evil was despicable, and the Spectre taught it the concept of revenge. Infuriated, the being sought to assault Heaven to demand answers from the Presence as to its existence, trampling all that it crossed paths with. This power was so huge, it caused Hell's main three figures - Lucifer, Azazel and Beelzebub - to form a triumvirate in order to defend themselves should the Great Evil Beast decide that it wanted Hell as its realm. A different faction, led by the Demons Three, banded together to follow the Great Evil Beast, whom they saw as the ultimate sin and the ultimate evil.
However, before the Great Evil Beast reached the gates of the Silver City of Heaven, it encountered the Swamp Thing, who taught it the concept of good and evil, life and death, intertwined so that one could not survive without the other. The Great Evil Beast then extended its hand, and something happened that nobody had foreseen; the Presence extended His. When both hands touched, both the ultimate light and the ultimate darkness merged, forming the perfect balance as a form of Yin/Yang.
The realm of the Great Evil Beast, an expanse of complete and utter darkness known as the Sunless Sea or the Shadowlands, has been referred to as the power source for shadow-manipulating characters such as the Shade (Richard Swift), his archenemy Simon Culp, the Shadow Thief, Nightshade, Ian Karkull, and Alan Scott's son Obsidian.
In other media
In the television series Constantine, archangel Manny (Harold Perrineau) warns John Constantine (Matt Ryan) that the Brujería plan to unleash an ancient evil known the "Rising Darkness" to the human realm. According to Papa Midnite (Michael James Shaw), this darkness will be unleashed when someone very close to Constantine betrays him in the future. At the end of the last episode, "Waiting for the Man", Manny releases Midnite from police custody and reveals that the Brujería works for him, which makes Manny the real mastermind behind the event of the story.
Whether the Rising Darkness is a reference to the Great Evil Beast remains unknown.