WandaVision pulled the curtain back on its Big Bad when it revealed that Agnes was in fact Agatha Harkness, a powerful witch from the Marvel Comics. Agatha clearly has an advantage against Wanda Maximoff in the MCU given the fact she put some kind of spell on her at the end of episode seven. But how does she fare against other Marvel magicians?
The only other major Marvel sorcerer in the MCU at the moment is Doctor Strange, but in the comics and in other Marvel movies, some of the most powerful characters in the Marvel Universe are also practitioners of magic. Agatha fares well against some of them, but others not so much.
Wiccan
Wiccan's powers in WandaVision so far seem limited to his mother's telekinesis - and perhaps telepathy - but in the comics, he is also a powerful magician. He has natural mystical abilities that allow him to alter reality, making him very powerful, though not on the level of some other magicians.
At least, for the moment. In one possible future glimpsed in the New Avengers comic, he becomes the Sorcerer Supreme. He has studied the mystical arts in the comics, continuing to grow his powers even more.
Nicholas Scratch
Nicholas Scratch is the son of Agatha Harkness in the comics and is one candidate for who Quicksilver might actually be in WandaVision. Scratch is a powerful warlock who led a secret community of magicians called New Salem. He is an incredibly powerful magician, able to fire bolts of force and energy, and capable of travel between dimensions.
He also sometimes wields something called the Satan Staff, which allows him to focus his magic and channel the power of other magicians through it.
Agatha Harkness
Scratch is powerful, but not as powerful as his mother. In the comics, Agatha Harkness is a powerful witch capable of staggering feats. One was to strip her son entirely of his magical abilities. Agatha did this after he tried to have her and others killed. Agatha also was able to place a spell on Wanda Maximoff that made her forget her children, Tommy and Billy, ever existed.
She did this after it was revealed that they were in fact magical constructs, created from fragments of the soul of the Marvel supervillain Mephisto.
Brother Voodoo
Brother Voodoo is one of the most powerful magicians in the entire Marvel Universe. He first appeared in Strange Tales #169 back in September 1973, the brainchild of writers Stan Lee, Roy Thomas, Len Wein, and artist John Romita Sr. His powers originate from the Loa, the spirit-gods of voodoo, and give him a broad range of abilities including possessing other people.
He is a powerful practitioner of voodoo and black magic who became Doctor Voodoo in 2009 when he took over the role of Sorcerer Supreme from Doctor Strange.
Magik
Illyana Rasputin, known as Magik in the comics, is one of the most powerful magic users in the Marvel Universe. She is essentially a god, though that it is limited to a demonic realm known as Limbo. Illyana was trapped there as a child and grew up tormented by the ruler of Limbo, Belasco.
Magik later supplants him and is able to control the dimension herself. Her magic is less potent on Earth, though still considerable. She wields the Soul Sword, one of the most powerful weapons in Marvel Comics. Magik appeared in The New Mutants movie, played by Anya Taylor-Joy.
Doctor Doom
Doctor Doom is one of the most heinous Marvel supervillains. He's also one of the most powerful. Beyond his interest and capacity in technology, he is equally proficient in the mystical arts. After learning magic from Tibetan monks, he became capable of energy absorption and projection, manipulating electricity, creating protective shields, dimensional travel, and more.
Doctor Doom has enough power and ability to become the Sorcerer Supreme in the comics, a fact that Doctor Strange admitted himself in New Avengers #51.
Hela
As an Asgardian, Hela has a mystical advantage over most. But her power goes far beyond the average in any realm. She can create limitless astral projections, fire bolts of energy from her hands which can age or kill Asgardians, and create illusions.
Most importantly, as the goddess of Death, she can claim any soul or command any of the dead in the realm of Hel. Hela first appeared in Journey into Mystery #102, created by writer Stan Lee and artist Jack Kirby. Cate Blanchett portrayed the character in Thor: Ragnarok and Hela certainly made her mark on the MCU.
Loki
Another powerful Asgardian with perhaps even more capability in magic is Loki. In the comics and in the MCU, Loki has been shown to be capable of energy projection, the creation of force fields, flight, hypnosis, illusion casting, and inter-dimensional teleportation.
Beyond that, he is able to trick powerful beings like Surtur, a Fire Demon and lord of Muspelheim, as well as break free of Celestial technology. The Celestials are among the most powerful cosmic beings in the entire Marvel Universe, meaning Loki is incredibly powerful.
Doctor Strange
Dr. Stephen Strange is generally considered in a class by himself. The Sorcerer Supreme draws power and energy from the Eye of Agamotto and other sources, allowing him to cast a variety of complex spells. He also wields mystical artifacts including the Cloak of Levitation which allows him to fly.
Perhaps his most considerable abilities are universal awareness, which is the perception of time and space and being able to cross dimensions, as he did in the first Doctor Strange movie, going into the Dark Dimension to confront Dormammu.
Scarlet Witch
Wanda Maximoff is arguably the most powerful magician in the Marvel Universe. She proved that on numerous occasions where she manipulated reality to her will. The most stunning example of this occurred in House Of M, one of the comics that influenced WandaVision.
In that comic, Wanda changed reality so that her lost children were still alive and the Maximoff family was in control of the world. When that failed, she lashed out, and erased the vast majority of mutants from existence with three simple words: 'No more mutants.'