One Below All

FULL NAME
Inapplicable
ALIAS
The One Below All
Satan
Cosmic Satan
The Devil
Devil of Devils
Breaker of Worlds
Angra Mainyu
The Morningstar
The Lightbringer
Saimael
The Beast Master
Father of Evil
Harbinger of Darkness
Bringer of Oblivion
The Anti-God
God of Evil
The One True Anti-God
Propagator of Sin Infinite
Ill Intent That Dwells in All
The One Whom All Creatures Fear
Progenitor of Monsters

ORIGIN
Marvel Universe
OCCUPATION
Demonic counterpart of the One Above All
POWERS / SKILLS
Anti-God physiology
Absolute Destruction
Absolute Immorality
Avatar Creation
Omnimelevolence (Is the embodiment of all evil and hate in the marvel Universe)
Gamma radiation manipulation
Meta disaster manipulation
Omnipotence (limited by inability to exist outside its native reality without a gamma-radiated host)
Omninescience (he is a mindless beast who knows nothing and only cares about destruction and death)

GOALS
Break free from its realm.
Destroy the omniverse.

CRIMES
Mass omnicide
Possession
Attempted omniversal destruction

TYPE OF VILLAIN
Cataclysmic Supreme Being

The One Below All is one of the overarching antagonists of the Marvel Comics universe, specifically serving as the main antagonist of the Immortal Hulk series. It is the opposite of creation and the dark reflection of existence.

The One Below All is the direct antithesis and evil half of the One Above All. This has radically altered Marvel's cosmology since this makes it Marvel's first true "Anti-God", and as such, it is the unequaled embodiment of destruction, wrath, and chaos, only challenged or matched by his brethren entities: Knull, Chthon, Shuma-Gorath, the Black Winter, and the First Firmament, as well as its good version, the One Above All. Various demons or other entities, namely Mephisto, Dormammu and the Serpent among others, have masqueraded as it for untold centuries, nonetheless ever aware and terrified of it in its various absences. The One Below All is also the true entity behind the mutagenic factor of gamma radiation in Marvel, creating the gamma-mutates (of which Hulk is obviously the most famous and powerful). It was this very revelation that drove Brian Banner insane, as he believed his son carried a "monster gene," having caught a glimpse of the One Below All during his own experiments into gamma radiation.

The One Below All is the alter-ego and the other face of the supreme creator and god, the One Above All. Just as there must be creation, there must also be destruction, and the One Below All's purpose is to be the destruction in the cycle of death and rebirth in the multiverse. While the One Below All is a separate identity from the One Above All, they are both two halves of the same supreme being and each acts as a counter/foil to the other. Every time a multiverse is created by the One Above All, entropy begins and the One Below All influences all the destructive beings in the multiverse to push everything to destruction.

As revealed in The Incredible Hulk #3, the One Below All was created as a manifestation of the One Above All's rage towards the Mother of Horrors. The Mother of Horrors was the only being in creation that the One Above All did not create, and she gave birth to a son named Udru to challenge him. The One Above All's heart was filled with anger, but because his only weapon was love he could do nothing. Thus, his rage transformed him into the One Below All, which blinded Udru and cast him down to Earth in its fury.

So far, the One Below All has no set "true form", but has very brief appearances where it can take seemingly any form it desires, though it favors the use of extremely abstract and terrifying visages.

There's no doubt it could further play on its dreaded reputation as the possible "true" Satan of the Marvel multiverse.

Despite its Satanic nature, the One Below All's apparent "true form" is actually a gigantic mass of green smoke and resembles a living gamma-bomb explosion in many ways, which is very likely symbolism of the One Below All's nature as both an embodiment of destruction and the hidden, malevolent intellect behind the mutagenic nature of gamma radiation in Marvel.

So far, the One Below All is considered an all-powerful demonic entity of unparalleled might. Even Mephisto, often considered the closest Marvel has to a Devil figure, stated that the One Below All is far beyond his power and that even if he wished to act against the entity, he would fail. This easily ranks the One Below All as one of the most powerful entities in Marvel's history. This goes even further with the revelation that the One Below All is the other face/alter-ego of the One Above All, the supreme entity and creator of the multiverse. As both the One Above All and the One Below All are revealed to be the two separate faces/identities of the same omnipotent being, the One Below All has no superior and is technically only one equal.

It is also revealed that despite the entity's immense power, it can only manifest via the Green Door or gamma-mutated beings such as the Hulk. Indeed, it was the Hulk who was necessary to unleash the One Below All from its dark domain in the first place.

The One Below All is one of the most mysterious and powerful entities to ever arrive in the Marvel multiverse due to its immense power. As it is the dark alter-ego/face of the One Above All, its power is limitless and unsurpassed though as the aspect of destruction it can only alter or destroy but never create.
Because of its name, many suspected this entity to be the evil half of the One Above All, or an equally powerful (but evil) deity, which has since been confirmed as a reality.
There are numerous incidents within the series that suggest Hulk himself is either the host for the One Below All or may even be the entity itself. This is only half-true, as Hulk is actually the one who manages to defeat the entity, by seemingly killing its host—Brian Banner.
The One Below All is the embodiment of destruction, but unlike other destroyer deities and personified forces, it does not represent natural decay, death, destruction, or entropy as part of a natural cycle. Rather, it is instead an outside force acting on reality and not as a force of nature it represents, as it carries out the act of unmaking things willingly, deliberately destroying them.