Abaddon in demonology, was chief of the demons of the seventh hierarchy. He was called The Destroyer and, in the Book of Revelation, St John called him the King of the locusts (Rev 9: 7-11).

The Thanksgiving Hymns—a copy was also found in the Dead Sea Scrolls—tells of "the Sheol of Abaddon" and of the "torrents of Belial [that] burst into Abaddon". The Biblical Antiquities of Philo mentions Abaddon as a place (sheol, hell), not as a spirit or demon or angel. In Paradise Regained, Milton also uses Abaddon as a place—the pit. It appears to have been St. John who first personified the term to stand for an angel. In the 3rd century Acts of Thomas, Abaddon is the name of a demon, or the Devil himself. Abaddon has also been identified as the angel of death and destruction, demon of the abyss, and chief of demons of the underworld hierarchy, where he is equated with Samael or Satan. In magic and alchemy, Abaddon is the Destroying Angel of the Apocalypse. In Barrett's The Magus, Abaddon is pictured, in colour, as one of the evil demons. In Medieval legend, Abaddon was considered as a synonym for Hell and/or the ruler thereof, and in Revelations 9:7-11, he was the Christian angel of Hell, Michael. The Hebrew word abadon, from which the name is derived, means "destruction" (Job 26:6 and Psalms 88:11).

Not long after Judeo-Christian teachings taught the name of this demon, Abaddon referred to the pit or cave that was used in mystery religions and schools as a rite of passage into the greater mysteries. Often the experience would entail the use of ritual substances that put the aspirant into an altered state in which he or she could receive divine revelation. Because the experience was sometimes unpleasant, this rite came to be viewed as being "hellish." However, it was considered absolutely necessary so that the seeker may become pure enough to encounter the "mind of God", as an angel is described as the "Angel of the bottomless pit who binds Satan for a thousand years".

In occultism and esoterism, Abaddon is related to blood red, brown and green colours, winter, the month of January, Saturday, intuition, sacrifice and challenge, the ruby and the sword. His Tarot symbol is the one of judgement.