The Darkness

The Darkness is a proto-primordial evil entity which has always existed, before God, Death and Creation itself. With His archangels by His side, God entered into a vicious war against the Darkness. Unfortunately, not even the combined might of God and the archangels could destroy the Darkness and so God succeeded only in sealing it away using the Mark of Cain as a lock and key.

When Rowena used a spell from the Book of the Damned in order to free Dean Winchester of the Mark, the Darkness was unleashed once again.

History
According to Death, before there was any light or life there was only the Darkness. Death credited this entity as a powerful amoral destructive force that obliterated anything in its path. God and his Archangels battled with this ancient evil known as The Darkness in a terrible war. He eventually sealed it with a mark that later would be called the Mark of Cain. He then gave the mark to Lucifer to guard. The Mark however showed itself to be a curse; the Darkness still able to exert a kind of influence through it and it corrupted Lucifer, leading to a chain of events that would see Lucifer cast out of Heaven, then Lucifer passing on the mark to Cain who then millennia later passed it on to Dean Winchester.

Present Day
The Darkness was eventually freed with the destruction of The Mark of Cain, where it rained down destruction and made a move to consume everything in its path.

It is unknown whether the darkness is an intelligent being or some kind of semi conscious force.

Powers & Abilities

 * Immortality - According to Death, the Darkness predates God and possibly even Death himself as well and cannot die.
 * Nigh-Omnipotence - While its full powers are unknown, it managed to battle against God and the archangels for an unknown amount of time, and Death was willing to make sure the Mark of Cain, the lock on the Darkness, wasn't broken.
 * Super Strength - Considering its ability to temporarily stand against the combined might of God and His archangels, the Darkness can be presumed to be unimaginably strong.
 * Flight - The Darkness, while disembodied, can fly in a similar manner to demons and angels without a vessel.
 * Invulnerability - Considering its ability to stand against God and His archangels, the Darkness can be assumed to have an immense resilience for physical and supernatural attacks that likely constitutes invincibility.
 * Corruption - The Darkness, through the Mark, corrupted all who bore it. It caused Lucifer to become jealous of Man, it drove Cain to become a Knight of Hell, and its influence was strong over Dean as well.

Weaknesses

 * God & Archangels - Only God, with the combined strength of the archangels, was strong enough to bind the Darkness. With God missing, Gabriel AWOL, Raphael and Death dead, and Michael and Lucifer locked in Lucifer's Cage, there is currently no known being or force powerful enough to stop the Darkness.
 * The Mark of Cain - The Mark of Cain was the "lock" to the prison that held the Darkness back. As long as one person bore the Mark, the Darkness would remain sealed. With its removal, the Darkness was set free once more.