Phase Three in the Marvel Cinematic Universe made it clear Thanos was the big bad all along. With his defeat in MCU can make the next Marvel supervillain.

The MCU machine isn’t slowing down. With one of the biggest breaks since the early days of Phase One, it is understandable to think Marvel has slowed or is unable to keep up the pace they were going at for the past decade. This is far from the case. The MCU is gearing up, taking the downtime to develop Disney+ series, movies, and who knows what else. As fans wait, there is a lot of talk about characters that could break onto the screen.

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A contentious part of the MCU has been "weak villains." With their huge reserve of the source material, they have plenty of villains to pull from. Here is a list of the top 5 villains marvel can use (and 5 villains that should never be on screen).

Shouldn't Happen: M.O.D.O.K.

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M.O.D.O.K. stands for Mental (/Mobile/Mechanized) Organism Designed Only for Killing. M.O.D.O.K. began life as George Tarleton, a scientist at Advanced Idea Mechanics (A.I.M.) and is the poster child for what happens when the line between genius and madness completely disappears.

Used as the Petrie dish for A.I.M. experimenting with mutation against his will Tarleton was left as a giant head, with no actual body, just tiny appendages. He gets around in a mechanized, heavily armed floating chair.  In the comic books, he's a great villain, worthy of sinister schemes and smarter than most villains and heroes.

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No matter how great a foe he may be on the printed page, there is not much you can do to make movie audiences take a huge floating head seriously - no matter how deadly he is. Especially when he has tiny T-Rex arms.

Could Happen: Dracula

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Weird but true, Dracula is a villain within the Marvel multiverse - and he is an awesome one. Vlad Dracula in the comics is the same one Braham Stroker created. He gains some powers within the multiverse, eventually becoming known as the ruler of Earth’s vampires, but there is not much the Marvel writers had to do with him.

He's an OG villain; all they had to do was play him off the right characters. Throughout his Marvel tenure, he has faced just about everyone, and his main adversaries are Deadpool and Blade. Since both these have entered the MCU, Dracula could the ranks of MCU villains. With the screen history the Dark Lord has, it could be a difficult battle, but one that would pay off so well.

Shouldn't Happen: Hyperion

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Hyperion has many iterations within the Marvel world. Posed as both a hero and a villain, in the grand scheme of things, many see him as falling onto the villain's side. Hyperion is another one better on the page then he would be on the screen.

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Known as the “Superman” of Marvel with his superhuman powers and shady history, the MCU will likely continue to shy away from Hyperion. He would be another one-dimensional villain, which is the last thing MCU villains need. Also, some fans will be resistant to him as a villain if they are fans of the hero storylines. He presents far too many potential problems to give him screen time.

Could Happen: The Lizard

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With Sony and the MCU currently sharing the Spider-verse, Dr. Curtis “Curt” Connor could make an entrance onscreen. Connor spent his career working on a serum that would give him the ability to regrow his arm, which he lost in an explosion in the military. Comprised mainly of Lizard DNA, during a mishap the serum melded with his DNA, turning him into The Lizard - a vicious monster bent on destruction and world domination.

As long as Sony and Disney/the MCU continue to play nice and share the Spider-verse, there is the possibility that this beloved villain could burst onto screens as one of the most anticipated MCU villains to date.

Shouldn't Happen: Void

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Robert Reynolds, a harmless high school student, took a potion and gained superhuman powers turning him into Sentry - all that is light and good. This power is driven by emotions and could destroy him if not checked. As a result, another persona was created to counteract that effect - the Void. For everything the Sentry is, Void is the opposite - darkness, and evil.

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For every person saved by Sentry, one will be killed by Void. Though a very complex and developed character, this is just too dark for the MCU. It would lead to problems with how to defeat Void and staging the showdowns. It’s another story that only works on paper.

Could Happen: The Enchantress

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Asgardian by birth Enchantress is a goddess. She wields Asgardian powers and uses them to pursue her goal of infinite power. Though she has not yet appeared on screen, her sister Lorelei had an arch in Marvel’s Agents of Shield first season. She uses her looks to attract pawns to her side and then controls them with her powers. She uses this in her quest for domination.

The Enchantress would make for an interesting storyline within the MCU villains, bringing another powerful and formidable female to the forefront of Marvel villain’s names.

Shouldn't Happen: Galactus

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Galactus is one of Marvel's top villains and is simply too powerful to work onscreen. He makes Thanos seem like a hairdryer with the booster button on. Galactus was initially a humanoid from the planet Taa named Galan. His planet was paradise, excelling in all things social and scientific. Before his planet finished forming completely, the Big Bang destroyed everything except Galan.

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Galactus is the ultimate cosmic being, consuming life force energies to satiate his ever-growing hunger. He has never truly been defeated, just weakened. He is driven by neither good nor evil, but the will to survive.

Could Happen: Red Hulk

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General Thaddeus Ross is an established character, so it's hard to envision how they could make him into the Red Hulk. Red Hulk is a popular character and it is easy to see that if the MCU continues with the Hulk storyline, he may be needed, so they could investigate it.

With the possibility of the Leader out there (as teased at the end of The Incredible Hulk), it is possible to bring this character on as an MCU villain. Though it might be hard to imagine them rewriting the history, it would make for an interesting onscreen storyline.

Shouldn't Happen: Molecule Man

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Molecule Man is another that is too powerful for screen time. Lab tech Owen Reece was a bitter man who felt the world owed him and when a machine he was working on malfunctioned, it changed his DNA at a molecular level. He was left with the ability to manipulate all molecules, even forming life out of the molecules around him.

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There is not much to do against that. He isn’t used in the comics much because it is hard to come up with scenarios that could beat him. It is not likely they will put that onto the screen.

Could Happen: Dr. Doom

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Victor Von Doom hails from the small country of Latveria. He has a super-genius intellect and super-insane jealousy issues. Doom will cure issues people have with the MCU villains as one dimensional, as being driven by a point or whatever other label people throw onto them. Doom isn't driven by wanting to rid the world of a perceived wrong. He's not attempting to solve suffering or overpopulation in what he feels is a fair and non-partisan way; he is selfish.

Driven by his belief that he's smarter and more capable than everyone,  he is arrogant, caring only for himself. Even with all this, Victor Von Doom is heralded as one of the most popular Marvel villains. With the Fox acquisition, he could rocket to Thanos level dimensions in the world of MCU onscreen Villains.

NEXT: MCU: 10 New Characters Who Could Make Surprise  Appearances In Phase 4