The Marvel Cinematic Universe has released a good two dozen films since 2008, and in that time the studio has given the world some truly powerful villains. In order for a villain to be compelling, they need to offer enough of a challenge to the heroes, or they will be boring and easily forgotten. Fortunately, the MCU is littered with powerful foes, many of whom are singularly more powerful than the heroes they go up against.
There are tons of villains to choose from for a list like this one, but determining the strongest Marvel movie villains is no easy task. This list comprises the biggest and baddest bad guys the MCU has to offer, and it's up to you to determine who is the strongest of them all!
Dormammu is a being from and ruler of the Dark Dimension who possesses immeasurable power. He has existed since the beginning of time, and his only desire is to conquer all of reality by merging his dimension with the MCU, otherwise known as Earth-199999. Doing so requires acolytes, and Dormammu finds willing subjects in Kaecilius and his zealots. When they succeed in initiating the transition that will bring Dormammu to Earth, Doctor Strange steps in to stop him.
Dormammu is caught in a time loop with Strange, and no matter how many times or ways Dormammu destroys Strange, the loop resets, trapping him within a pocket of time. To escape, Dormammu agrees to leave Earth forever, and he takes Kaecilius and the zealots to torture forever. Dormammu's power is essentially incomprehensible, as his abilities cross time, space, and reality.
Thanos is the sole-surviving member of his species from the planet Titan. Before it was destroyed, he tried to get his people to sacrifice half their population, which would eliminate the growing lack of resources the planet faced, but he was denied. Ultimately, Titan did fall, and Thanos began his mission to "help" other worlds by slaughtering half of their populations so that they wouldn't suffer the same fate as his own.
This makes him an enemy of all life, but it isn't until he begins acquiring the Infinity Stones that he becomes a threat to literally all life in the universe. His goal is to quicken his mission by obtaining all of the Stones and snapping his fingers, which would then cull half of all life from existence. This includes all single-cell and multicellular life, so plants, animals, people, and everything else is at risk.
Thanos manages to carry out his snap, but he is later hunted down by the remaining Avengers and is beheaded. Through some time travel shenanigans, he returns to battle the entire might of the Avengers, Wakanda, the Guardians of the Galaxy, the Ravagers, and more at the Battle of Earth. His goal at this point is to completely reshape the universe in his image, but he is stopped by Iron Man, who takes the Stones and snaps Thanos and his army from existence at the cost of his own life.
Hela is the first-born daughter of Odin, but when her eagerness for battle grows too great, Odin banishes her to the realm of the dead. There, she becomes the Goddess of Death, and she is unable to return until Odin's passing. When he perishes, she manifests herself in the earthly plane only moments later, meeting Thor and Loki at the site of their father's demise.
Hela demands that they acknowledge her superiority, but the boys aren't having any of that, so they draw their weapons. Hela manifests ornate swords from thin air and destroys Thor's hammer Mjolnir without breaking a sweat. She draws her power from Asgard, and after knocking Thor and Loki out of the way, she makes it there. She immediately begins wiping out Asgardian warriors, and manages to singlehandedly slaughter the entire Asgardian military.
She proves she is invincible, and Thor only manages to get away from her with his strongest attack, which doesn't even scratch her. Ultimately, Asgard has to be destroyed to take her out, so Loki throws Surtur's crown into the Eternal Flame and initiates Ragnarok. Surtur defeats Hela by driving his blade through her to the core of Asgard, destroying it forever.
Surtur is the ruler of Muspelheim and the prophesied being who will initiate Ragnarok, bringing about the destruction of Asgard. Odin defeated Surtur ages ago by taking the Eternal Flame from him and banishing him and his whole race to Muspelheim. It is there that Thor discovers Surtur is still alive, so he knocks his crown from his head, destroying him.
Surtur returns when the prophecy is fulfilled by Loki, who takes the crown of Surtur and places it within the Eternal Flame. Doing this causes Surtur to return to his normal size, which is about as big as a mountain, and he goes about destroying the various buildings of Asgard.
While this is happening, Thor and his allies, along with the remaining population of Asgardians, manage to escape, leaving Surtur to deal with Hela. He easily thrusts his blade through Hela and into the core of Asgard, destroying the home of the Asgardians forever.