During his years as Sorcerer Supreme, Doctor Strange has come up against plenty of villains. Some of them time and time again. It goes without saying that some of these antagonists are larger threats to Strange than others.

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The greatest enemies for Doctor Strange are the ones that push him to the limit. The ones that force him to think outside of the box. The ones that make it seem like he’s going to lose. Those ones are the most iconic, and without a doubt his worst enemies out there. They're also some of the biggest, baddest villains in Marvel's repertoire.

10 Umar

Umar is the daughter of Sinifer, sister of Dormammu, and mother of Clea. Her family ties alone would have been enough to force Doctor Strange to cross her path, which explains why they come up against each other again and again.

Umar was originally born a Faltine, but over time she was forced into her more mortal body. That's a good thing for Doctor Strange, as this change gave him the upper hand. Still, Umar has proven that she's not against using her own child, Clea (Doctor Strange's once lover) to force his hand. Frequently, Umar will be seen working for or with her brother, Dormammu.

9 Kaecilius

Kaecilius opposing the heroes in Doctor Strange

The Kaecilius seen in the comics and the one seen in the MCU are somewhat different from one another. He still goes up against Doctor Strange (with a fair amount of frequency), but his reasons are different.

Kaecilius is one of Baron Mordo's followers. He is not a leader himself, nor does he seem to be the type to do the plotting. He will happily follow Mordo's orders, though, including going after the Ancient One (while he was alive) and Doctor Strange.

8 Baron Mordo

Even if you've only ever seen Doctor Strange, you'll know that one of Strange's enemies is Baron Mordo. While the two may have the same instructor (the Ancient One), that is where their similarities end.

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Baron Mordo is a master of the darker side of magic, and isn't afraid to summon demons or other dark entities to his gain. Between that and his other nefarious schemes (such as trying to kill the Ancient One), the two are constantly butting heads.

7 Nightmare

Nightmare is exactly what his name implies. He is the personification of nightmares, and as such, is an entity similar to the Eternals. Nightmare has been an enemy of Doctor Strange's since the early years (back when the Ancient One was still alive).

The two first met in the dream realm, which shouldn't be a surprise to anyone. Here Nightmare trapped Doctor Strange, forcing him to break out. Their battles are brief but somewhat frequent, as Nightmare has a habit of holding victims hostage through their dreams.

6 Morgan Le Fay

Morgan le Fay with arms raised and looking down in Marvel Comics.

Morgan Le Fay may be a character of folklore, but she is also a known entity within Marvel comics. She's still the brilliant sorceress many of us know her as, one who has a talent for creating major events that attract the attention of magical heroes like Doctor Strange.

Doctor Strange is not the only enemy to Morgan Le Fay, but considering her plans sometimes involve trying to steal the bodies of fellow superheroes (such as Spider Woman) this isn't surprising. Morgan Le Fay is powerful enough that she could become the Sorceress Supreme, should her focus shift to a more protective stance.

5 Loki

Kid Loki as a Young Avenger in Marvel Comics

Loki may seem like he only goes up again Thor and the Avengers, but in truth the god of chaos is quite talented at getting around. He's come up against Doctor Strange on more than one occasion, with varying degrees of success.

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Most recently, Loki took the mantle of Sorcerer Supreme away from Doctor Strange. The act threw Doctor Strange into turmoil, and left him desperate and determined to make things right. It was later revealed that the whole thing had been another one of Loki's tricks...which is about what we expected.

4 Dormammu

Dormammu is an antagonist of Doctor Strange's who constantly appears. He even made his way into the movie, as most already know. Dormammu is the ruler of the Dark Dimension (most of the time, at least), and as such he has good reason to go after Doctor Strange and everything (and everyone) he protects.

Doctor Strange has prevented Dormammu from taking over his dimension on more than one occasion – including the very first time they met. Over the years the power scales of these two combatants has varied, but that hasn't stopped them from wanting to fight yet again.

3 Mephisto

mephisto in doctor strange #15

Mephisto is the ruler of a pocket dimension eerily similar to how most would picture hell. Conveniently, he happens to call this dimension Hell (and sometimes Hades). To be clear, this dimension isn't actually Hell – he just calls it that in order to get his hands on more human souls: a fact that has forced Doctor Strange to step up on more than one occasion.

The most recent and iconic appearance of Mephisto is Doctor Strange: Damnation. Here, Mephisto took all of Las Vegas to his domain (exploiting a spell Doctor Strange had just cast). The Avengers and other heroes got wrapped up in the mix, forcing Strange to save them all.

2 Empirikul

The Empirikul is a more recent antagonist of Doctor Strange's. The Empirikul are lead by a man called the Imperator. He blames magic for all of the loss and tragedy in his life, and thus he has sought to destroy it. And he came closer than many of us would have liked.

The Empirikul are an army of robots, and they've been designed to seek out and destroy all magic, across all dimensions. Because of their tactics and their elimination of magic in the air, they were an incredible threat to Doctor Strange and his allies. They forced Doctor Strange to think and act differently than he ever has before, proving their threat level.

1 Mister Misery

Mister Misery is the worst of Doctor Strange's enemies for a very specific reason. Mr. Misery is quite literally an enemy of Strange's creation. You see, magic has a cost. And Doctor Strange, as the Sorcerer Supreme, has had to cast a lot of magic in his days. One of the things he attempted to do to shift the cost...well it resulted in Mr. Misery.

Mister Misery is formed by all of the pain and suffering in Doctor Strange's life. Up until the point where he gained his freedom, he had been known as the 'Thing in the Cellar.' If not for the attack by the Empirikul, Mr. Misery may have stayed locked up for ages (until he got strong enough to free himself). But this being of misery happily took advantage of the opportunity to attack a magically-weakened Doctor Strange.

NEXT: Marvel: 10 Questions About The Ancient One, Answered