Here is a pretty good list of some of Marvel's most powerful beings. Notice where Ultron is on the list
I'm sure none of this matters in the marvel cinematic universe though
1. One-Above-All
The one-above-all is the god of the marvel omniverse,
he could even beat every single character at the same time even characters that aren't from marvel.He's above any possible level of strength,speed,energy projection,durability,intelligence,and fighting skill.
2. The Fulcrum
The fulcrum is non other than Jack Kirby himself,the fulcrum is half of the one-above-all.He is also the strongest character ever second alone to the one-above-all.
3. Heart of the Universe
The heart of the infinite made thanos have a piece of the one-above-all's power which is stronger than every character ever combined even pre retcon beyonder and the living tribuanl and pre retcon molecule man. Thanos with the HOTI even absorbed every entity in the marvel universe,eventhe livng tribunal,infinity,and eternity.He discovered that fundamental that would have otherwise destroyed the universe,but thanos sacraficed himself in order to fix it.Only adam warlock knew about this sacrafice
4. Beyonder
(pre retcon version)Pre retcon beyonder is the strongest in the history of marvel and he even beat almost every cosmic being and they were at mercy when they lost against him,pre retcon beyonder is even stronger than pre retcon mole cule man and the living tribunal toghether.
5. Molecule Man
(pre retcon version)Pre retcon molecule man was the most powerful being in the marvel multiverse stronger than the living tribunal and he even had full control of all matter and energy in the entire marvel universe.
6. Living Tribunal
The living tribunal is the master of the marvel universe and he is one of the strongest in the marvel multiverse.He even found the matter of the infinity gauntlet to beneath his concern and eventually disabled it.
7. Akhenaten
Akhenaten was an egyptian pharaoh in circa 1300 bc and hes so strong,that he is on the levels of the living tribunal and he is more powerful than everyone else below him on this list combined.
8. Nemesis
Nemesis is the being that split into the infinity gems.Even her withoput full power could beat everyone below her on this list combined.
9. Sise-Neg
Sie-neg absorbed all magical energy in the entire marvel universe during his quest to become god,he was intending to recreate the universe in his own image.He is even stronger than the infinity gauntlet,the cosmic cube,and alien entity.
10. The Alien Entity
Alien entity is a mysterious being that searches for the meaning of life ever since he was mortal and he came to reed richards for help and with his aid alien entity became the founder of a new reality.
11. Thanos
(with the infinity gauntlet)You all know that most villains threaten to destroy the universe but thanos is one of the only villains who could actually do it,he once gained the infinity gauntlet which gave control of time,space,reality,and the souls of others,unlimited strength, and psychic powers.He also was able to destroy half of the population in our universe just by snapping his fingers. Thanos also beat silver surfer to the brink of death and even destroy planets with a few of his blows,he also made the rainbow bridge of asgard shatter which caused all the skyfathers including zeus and odin to be trapped on asgard.The infinity gaunlet also have the power of eternity,infinity,mistress love and master hate,uato the watcher,galactus, stranger, master order and lord chaos,the celestials, and kronos. He even captured several of the cosmic beings(such as galactus and stranger).
13. Ultimate Nullifier
The ultimate nullifier is an extremely,ultimately powerful weapon and artifact and it could beat everyone else who is behind it on this list including abraxas.
14. Abraxas
Abraxas is ultimatley powerful even his own father wasnt able to stop him mad jim jaspers cant even stand a chance against abraxas.Only the ultimate nullifier can defeat him.
15. Mad Jim Jaspers
Mad jim jaspers is an extremely powerful reality warper and he defeated eternity and thats why hes ahead of eternity on this list.
16. Eternity
Eternity is the brother of infinity and he is omnimpotent and omnimscient,eternity is also stronger than everyone else behind him on this list.
17. Infinity
Infinity is the sister of eternity and she is also onhis levels,she is stronger than oblivion and death.
18. Death
Death is the female version of oblivion and she is onthe levels of infinity,oblivion,and eternity.She also is immortal and she can also bring the dead back to lfe,she also is immensley powerful and can destroy the entire cancerverse.
19. Oblivion
Oblivion is extremely powerful and is the male counterpart of death,he has many agents such as malestrom,mirage,deathurge.He also is devoid of all mater and energy.Oblivion is also on the levels of death,infinity,and eternity.
20. The Many-Angled Ones
The many-angled ones have destroyed most of the celestials and they came from the cancerverse, a reality exact opposite from the marvel universe.
21. Celestials
The celestials such as arishem,exitar,the on above all,scathan,and tiamut of extremely powerful beings they are even far more stronger than odin,galactus,the watchers and many more.Odin even tried to beat them with the destroyer armor but the celestials melted the armor and odin failed.They all beings of extremely owerful cosmic energy.
22. Goblin Force
The strongest force in the universe and even killed galactus.The goblin force is so strong that it took the combined might of the celestials to destroy it.
23. Phoenix Force
The phoenix force is one of the most powerful forces in the universe,this force could even beat all the watchers.
24. Watcher
The watcher is a very old race and is a rival od the celestials.He also made hulk one of the smartest on earth and he could also destroy planets and galaxies.He also has a greater knowledge than galactus and would beat the vishanti and cyttorak.
25. Cyttorak
Cyttorak is an extremely strong and powerful sorcerer stronger than doctor strange,mephisto,dormammu,and even the vishanti and zom.He also is even more powerful than galactus and he is the strongest magical being inthe entre marvel universe.Within his dimension his powers are limitless.
26. Vishanti
The vishanti are mystical beings of immense power andthey are stronger than galactus.Oshtur is the strongest out of the three.Even just one of the members of the vishanti can challenge galactus.
27. Galactus
Galactus was the last survivor of the galaxy that existed before the big bane,he is also a world eater,he eats planets to survie.He also has extremely powerful power cosmic.Galactus also posseses vast knowledge and unlimited cosmic power cosmic.
28. Stranger
Stranger is known to be one of the strongest in the universe and is on the levels of galactus.He also can emit powerful energy blasts and erect impenetrable force fields.
29. Tyrant
Tyrant is the strongest herald of galactus and is extremly powerful,so powerful that is strong enough to fight his master galactus but he would lose against galactus.He is also stronger than the elder gods.
30. Chthon
Chthon has been created billions of years ago and he is even stronger than the cosmic cube.He is portrayed the equivalent of the primal devil that pre-dates the judeo-cristian teachings.
31. Korvac
Korvac posseses a great amount of technology and cosmic powers.He also has acyborg body and brain and he took full control of galactus' ship,and he practicly became a god after downloading the power cosmic.
32. In-Betweener
In-betweener is the servant of master order and lord chaos and he posses a great amount of power and cosmic enrgy.
33. Dormammu
Dormammu has beaten mephisto and is stronger than doctor strange.He is also the lord of the dark dimension and has extremely powerful sorcery stronger than mephisto and doctor strange.Within his dimension their is no entity or being that can possibly stop him.
34. Mikaboshi
Mikaboshi is an abstract being stronger than zeus,surtur,and odin.He has immortality,shapeshifting,super strength,energy projections,and etc.
35. Surtur
Surtur is a fire demon that beat both thor and odin at the same time.Surtur also stands over 1000 feet tall.He is also a huge threat to asgard and an arche foe of asgard and thor .His strongest weapon is the twilight sword which is very powerful.
36. Odin
Odin created thor's hammer and is strong enough to fight surtur.He also is the strongest of all the sky fathers and has the odinforce.
37. Ymir
Ymir is the king of the ice demons and can make everything he touches turn into ice even air.He could also manipulate the weather around him and hes an arch foe of asgard.
38. Ego
Ego the living planet can travel through space and shoots cosmic energy from his eyes.He is even strong enough to fight galactus and he can create other being controled by himself.
39. Mephisto
Mephisto is pure evil and he rules a realm in hell.He is the marvel version of the devil,he also has extremely powerful sorcery.
40. Kronos
Kronos is the master of time and his mind became one with the universe.He also has very powerful cosmic energy.
41. Destroyer
Destroyer is an arch foe of thor and a herald of galactus who is stronger than any other herald but hes not stronger than tyrant.He also is capable of shooting powerful energy beams.
42. Eon
Eon is the father of epoch and has all the powers his son has but his son,epoch has not mastered them yet.
43. Epoch
Epoch is the keeper of cosmic awareness which gives him omnimscience.
44. Zeus
Zeus is the second strongest skyfather and he beat the hulk like it was nothing and caused his lungs to shatter.Zeus is also the king of all greek gods and is the father of hercules.
45. Onslaught
Onslaught posseses the combined abilities of magneto,professor x,franklin richards,and nate grey and he is a being full of very powerful energy.
46. Annihilus
Annihilus can make immature clones of himself when he dies and they can retain memories and experience so he could survive.He also wields the cosmic rod.
47. Silver Surfer
Silver surfer is stronger than any other herald of galactus but hes not stronger than destroyer and tyrant and his board gives him very powerful cosmic energy.He even beat thor and the hulk.
48. Heralds of Galactus
(not including silver surfer,destroyer,and tyrant)The heralds of galactus such as the fallen one,air walker,human torch,firelord,redshift,nova,terrax,and morg were strong enough to fight silver surfer and one of them died to save his master.They all also are very loyal to there master,galactus.
49. Sentry/The Void
Sentry has the power of one million exploding suns and has fought alot of powerful characters ssuch as world war hulk,galactus,and thor.Sentry also was ranked earth's strongest hero.The void is the alter ego of sentry and would do stuff that sentry would never do.The void causes millions of disasters and causes millions to die.He is a very evil demon.
50. Apocalypse
Apocalypse is the first mutant on earth and the most powerful.He also fought the entire x men roster alone.
51. Doctor Doom
Doctor doom is so strong that he is able to steal powers from galactus and odin.He is an experienced sorcerer and has highly advanced weaponry.Doctor doom is even stronger than hulk and thor.
52. High Evolutionary
High evolutionary has a very powerful intellect and is on the levels of apocalypse.
53. Grandmaster
Grandmaster is a very powrful elder of the universe and can heal other injuries and illnesses and is also immortal.Grandmaster is a couple thousand years old.
54. Captain Universe
Captain universe can shapeshift into any hero he wants and has very powerful cosmic energy.
55. Gladiator
Gladiator is the emperor of the shi'ar and he is even stronger than hulk,thor,and even adam warlock.He has very powerful heat vision and he is even faster than the speed of light.He has even fought the inhumans before.
56. Black Bolt
Black bolt is the ruler of the inhumans and he can unleash great destructive power by using his voice.Even a whisper of his is dangerous and can detroy a whole city and a scream of his can destroy an entire planet.
57. Doctor Strange
Doctor strange is the god of magic and the strongest sorcerer in the world,he is on the levels of odinforce thor.
58. Ultron
Ultron is very smart and powerful he is stronger than thor and the hulk.He also is the ruler of phalanx and he could control his victim's minds and maipulate their memories.
59. Mangog
Mangog is an arch foe of asgard and thor.He has returned to attack asgard several times.
60. Thor
Thor is the god of thunder and he is the son of odin.Thor can control the weather with his hammer.He is even stronger than hulk and beta ray bill and fought herucles and silver surfer.
61. Adam Warlock
Adam warlock posseses the soul gem, which enables him to sense the souls of others.He also could fly at incredible speeds.
62. Hulk
The hulk is incredibly strong and he has even fought wolverine,thor,skaar,and hercules.Hulk can also lift up to one billion tons.
63. Vulcan
Vulcan has powerful energy manipulation and even fought gladiator and black bolt.He was also once the emperor of the shi'ar but has been overthrown.
65. Beta Ray Bill
Beta ray bill is strong enough to face thor and he is also an alien beloning to a race known as the korbinites.