Seven Great Demon Lords

Their power was so great and so evil that they were confined to the Dark Area. Lucemon Chaos Mode instigated a rebellion in ancient times and was sealed there with many other Evil King Digimon; Daemon, once a high-ranking Angel, was deleted there for rebelling.

The Seven exist independently and keep a balance by not interfering with one another, though they have joined forces for a common goal.

A Super Demon Lord with seven legs, seven eyes and an eighth eye unlike the others: it contains all the sins of the Digital World along with the power to atone for them, nullifying the power of any Digimon with even a hint of wickedness.

Each of the Seven holds one of the deadly sins (Digimon Profile #026), and the Reference Book profiles of their X-Antibody forms name the matching Crown: of Pride, Envy, Wrath, Sloth, Greed, Gluttony and Lust.

Belphemon is said to be sealed in the deepest part of the Dark Area, and because its power is so immense, the Digital World's system put its data into Sleep Mode.

Digimon Profiles #026 and #035 and the official Digimon Chronicle X story place the Seven's stronghold in Cocytus, the single lowest layer shared by the Dark Areas of every Digital World, where each holds its own territory. Those they slay are never reincarnated and become their flesh and blood. GranDracmon and Gulfmon live there too, but neither belongs to the Seven.

In Digimon Chronicle X, the defeated Seven are dragged to Cocytus and absorbed by seven copies of Diablomon X, which fuse into Ogudomon X: Lucemon X's plan to destroy the whole Digital World. Once Jesmon GX cuts it down, the Seven return to Cocytus.