1 Thanos
Thanos is a fictional supervillain appearing in American comic books published by Marvel Comics. The character was created by Jim Starlin and Mike Friedrich. The character first appeared in Iron Man #55 and has been portrayed by actors Damion Poitier and Josh Brolin in the Marvel Cinematic Universe. Love his complex personality. Definitely not just one of those stereotypical villains, but one with real color in his character. I appreciate villains that you can actually understand, especially the ones complex enough that they make you question who you should root for.
I would think that Loki should be at the top because it's the "Greatest" villains and not the "Most powerful" but whatever. Thanos defeated all of the avengers, killed half of the population, and almost won once again in Endgame. He is undeniably the most powerful villain in the MCU.
He has become the greatest villain with the release of Infinity War. He's complex, interesting, and truly believes he's the good guy. That is an amazing villain to create, one who truly believes what he is doing is righteous.
Thanos is not only the best but darkest villain in marvel history.
He actually Wins...for now.
2 Loki
Loki Laufeyson, or Loki Odinson, is a fictional character appearing in the American comic books published by Marvel Comics. He is the adoptive brother and archenemy of Thor, and is known as the "God of Mischief". In the Marvel Cinematic Universe, the character has been portrayed by Tom Hiddleston. How is this possible? How is Loki not number 1? He is an amazing character, and the MCU NEEDS him. That's why he keeps coming back. This shouldn't even be a competition.
Loki isn't the most powerful, but he's the best. He "died" like, what, 3 times and came back? Awesome!
If Thanos was better, why doesn't he have his own TV Show or movie named after him? Truly, looks like Loki is better
How in the world did Ronan and Ultron get ahead of Loki?
3 Ultron
Ultron is a fictional supervillain appearing in American comic books published by Marvel Comics. He is most recognized as a foe of the Avengers, and has a quasi-familial relationship with several of their members, especially his creator Hank Pym. In the Marvel Cinematic Universe, he is portrayed by James Spader. I have no strings.
He is the best
4 Erik Killmonger
They made him somewhat sympathizeable. If one day, my uncle suddenly came into my house while I was out, but I knew he had been there cause I had seen his car, and I found my dad dead and the man he trusted missing, I'd probably do the same as well.
5 Vulture
Should be number 1
6 Red Skull
The Red Skull is a fictional supervillain appearing in American comic books published by Marvel Comics.
7 Hela
Cate's performance is SO amazing, that I forget Hela's main goal is just boring conquest.
8 Iron Monger
9 The Winter Soldier
James Buchanan "Bucky" Barnes is a fictional superhero appearing in American comic books published by Marvel Comics. In the Marvel Cinematic Universe, he is portrayed by Sebastian Stan.
10 Mysterio
Mysterio is a fictional supervillain appearing in American comic books published by Marvel Comics. He is most often depicted as an enemy of Spider-Man. He made his debut in The Amazing Spider-Man #13. In the Marvel Cinematic Universe, he is portrayed by Jake Gyllenhaal.
The Newcomers
? Kang the Conqueror
Kang the Conqueror is a fictional character appearing in American comic books published by Marvel Comics. In the Marvel Cinematic Universe, he is portrayed by Jonathan Majors.
The Contenders
11 Ego the Living Planet
Ego the Living Planet is a fictional character appearing in American comic books published by Marvel Comics. In the Marvel Cinematic Universe, he is portrayed by Kurt Russell.
12 Baron Zemo
Baron Zemo is the name of two fictional supervillains appearing in American comic books published by Marvel Comics. Not all villains have to be big, destructive colossal being with superpowers. Sometimes the most dangerous villains are the ones who are the smartest. Zemo may be underpowered, but he makes up for that with his manipulative skills. Don't forget that he is the one who master-minded the whole Civil War to happen between the Avengers.
I'm happy to see those villains on the top but zemo deserves to be higher. I think he must be in the top ten
I didn't like him much
13 Dormammu
I've come to bargain
14 Ronan the Accuser
Ronan the Accuser is a fictional character appearing in American comic books published by Marvel Comics. In the Marvel Cinematic Universe, he is portrayed by Lee Pace.
15 Abomination
16 Grandmaster
17 Purple Man
Sexily dark, complex and is David Tennant and is by far the most terrifying. He scares me as much as I'm crushing on him!
He's by far the most complex and compelling.
18 Amatsu-Mikaboshi
19 Galactus
Galactus is a fictional character appearing in American comic books published by Marvel Comics. Formerly a mortal man, Galactus is a cosmic entity who originally consumed planets to sustain his life force, and serves a functional role in the upkeep of the primary Marvel continuity.
20 Kingpin
Kingpin is a fictional supervillain appearing in comic books by Marvel Comics. He usually serves as an antagonist of Daredevil and Spider-Man. He made his first appearance in The Amazing Spider-Man #50, most well known for being the famous "Spider-Man No More" story. Kingpin himself should at least be in the Top 5. I honestly don't know any other MCU villain who is as developed and well-characterized, yet as menacing and intimidating as Wilson Fisk.
Also, a personal opinion of mine; he's my personal favourite MCU villain. Thanos is pretty good, but pretty overrated nowadays.
21 Doctor Doom
Doctor Victor Von Doom, better known as Doctor Doom, is a fictional supervillain appearing in American comic books published by Marvel Comics. The character usually is a villain of the Fantastic Four. He debuted in The Fantastic Four #5.
22 Alexander Pearce
Yes, he isn't a super natural being with cool powers or anything, but that doesn't make him a bad villain. Sometimes masterminds can be more dangerous then a overpowering, big guy with super powers. And this guy was as cunning of a mastermind as they come.
23 Kaecilius
24 Venom
Venom, or the Venom Symbiote, is an alias used by several fictional characters appearing in American comic books published by Marvel Comics, commonly in association with Spider-Man. I prefer the "Venom" one over the "Spider-Man 3" one.
25 Surtur