WandaVision may not have paid off a certain prediction for the final episode regarding Mephisto, the Marvel analog for the Devil, but it might have done one better. The book Agatha Harkness kept in her basement was revealed to be The Darkhold, a dark magic tome connected to another major Marvel demon, Chthon.
Mephisto and Chthon are two of the most powerful demonic entities in the entire Marvel Universe. Where do they rank against each other? Are they at the top of the food chain when it comes to interdimensional evil? There are many demonic beings in Marvel Comics, and all of them beyond powerful.
Zarathos
Zarathos is a demonic being who tortures and devours souls. Terrifying as that is, he ranks near the bottom of the demonic powers in the Marvel Universe. He first appeared in Marvel Spotlight #5 back in August 1972 and was created by writers Roy Thomas and Gary Friedrich, and artist Mike Ploog.
He's principally a villain for Ghost Rider, and in the 2012 movie Ghost Rider: Spirit Of Vengeance, a Marvel movie not part of the MCU, Ghost Rider is revealed to be the reincarnation of Zarathos himself.
Blackheart
Another Ghost Rider villain has major connections to Mephisto. Mephisto is a supremely powerful villain, and among his abilities is the power to conjure demonic beings like Blackheart. Mephisto created him as a son, born from all of his accumulated evil energy.
Blackheart would go on to be a problem for a number of Marvel heroes in the 90s, including Daredevil. Co-created by writer Ann Nocenti and artist John Romita Jr., Blackheart first appeared in Daredevil #270 in September 1989.
Nightmare
Nightmare was among the potential suspects for the true Big Bad of WandaVision. It's easy to see why he would have made sense in the beginning. Nightmare is the ruler of a Dream Dimension, and he is one of the Fear Lords, with the ability to draw power from the psychic energies of the subconscious minds of dreaming beings.
He roams this realm on a demonic black-horned horse named Dreamstalke. He's a major Doctor Strange villain and first appeared alongside his mortal enemy in Strange Tales #110 back in 1963. He was created by Stan Lee and artist Steve Ditko.
Surtur
Surtur is where the game really picks up for Marvel demons. Based on the fire giant Surtr from Norse mythology, he's less a demon than a god. Surtur is a fire giant native to the extradimensional plane of Muspelheim, the land of the fire demons and one of the nine worlds in Norse mythology.
He is at the center of the mythic Ragnarok cycle in Asgardian culture, which was depicted in Thor: Ragnarok in 2017, and as the destroyer of realms, is a serious player. Surtur the comic book character was co-created by the legendary comic book team of Stan Lee and Jack Kirby for Journey Into Mystery #97.
Null The Living Darkness
Surtur can destroy worlds, but his power is somewhat bound in the confines of the Nine Realms. This isn't the case at all for Null The Living Darkness. Null is a mystic life-form formed over the ages from the collective unconscious of 500,000 members of the extinct S'Raphh race.
He has a near-unlimited ability to manipulate the forces of magic, making him both wildly unpredictable and supremely dangerous. He is capable of interdimensional teleportation, restoration of spirits to the physical plane, and the reanimation and control of the dead.
Dormammu
Dormammu is perhaps the greatest foe of Doctor Strange. He is the ruler of the Dark Dimension and one of the most powerful beings in the Marvel Universe. He is an interdimensional entity composed of mystical energy that can be used to almost any end.
Dormammu is capable of many terrible things, including necromancy, the bestowing of power to others as he did with his one-time ally Nicholas Scratch, the son of Agatha Harkness, as well as the creation of demon lords to serve his terrible purposes.
Mephisto
Mephisto is one of the most powerful demons in Marvel Comics. Mephisto rules over the dimension of Hell, which he can alter to his will. He can claim and control souls. He can use magic on a scale that's beyond understanding, though he does have significant rivals in the Marvel Universe.
Mephisto is also capable of rewriting history, as he did when he erased Spider-Man and Mary Jane's marriage from continuity in the controversial event One More Day. Mephisto may appear on screen, but it's a Spider-Man story the MCU should avoid.
The One Below All
Mephisto's place in the demonic hierarchy in Marvel has been supplanted in recent years by The One Below All. This powerful and mysterious entity resides in the Below Place, the final layer of Hell. He is hidden behind The Green Door, and for good reason. Mephisto tells Doctor Strange that The One Below All is more powerful than he is.
The One Below All was created by writer Al Ewing and artist Joe Bennett, and first appeared in Immortal Hulk #5, during their recent and lauded run that has breathed new life figuratively and literally into the Hulk character and mythos.
Shuma-Gorath
The One Above All is trapped in the bottom of Hell. Shuma-Gorath once ruled the multiverse. Shuma-Gorath is an ancient force of chaos, the immortal, nigh-invincible, and godlike ruler of nearly a hundred alternate universes. He is a creature clearly inspired by the Cthulhu mythos of writer H.P. Lovecraft.
Shuma-Gorath can destroy entire galaxies with his will, putting him far, far beyond the capability of Mephisto or any other demon in the Marvel Universe, except for one.
Chthon
The Darkhold is so significant in WandaVision because it is the magical record of Chthon, the Lord of Chaos. He is a demonic Elder God who was the Earth's first practitioner of chaos magic, the magic that Wanda is now the most powerful practitioner of.
While trapped beneath Mount Wundagore, he attempted to use a young Wanda Maximoff as his earthly vessel. His interaction with her suffused her with chaos magic and amplified her latent abilities to make her one of the most powerful beings in existence.