In the world of fiction, characters like Thanos are also extremely powerful. He has the Infinity Gauntlet which gives him the power to control reality, time, and space among other things. He can wipe out half of all life in the universe with a snap of his fingers. His strength and the scope of his power are truly terrifying.
Superman is often considered one of the strongest. His powers like super strength, flight, and heat vision make him a force to be reckoned with.
The strongest beings often have superhuman strength. For example, Hulk gets stronger as he gets angrier, and his physical power is off the charts. They also usually possess some form of energy projection. Like how Doctor Strange can manipulate magic energy for various effects, from creating shields to attacking enemies.
Some of the most powerful fictional beings are the Q Continuum from 'Star Trek'. The Q are omnipotent and can manipulate time, space, and reality at will. In the world of Japanese anime, Goku from 'Dragon Ball Z' is also very powerful. His power levels keep increasing throughout the series and he can perform incredible feats of strength and energy projection. Another is Lucifer Morningstar from the 'Sandman' series. He is an extremely powerful fallen angel with a vast array of powers.
One could consider characters like Superman. He has super strength, speed, and various other powers. Another is Doctor Manhattan from 'Watchmen'. His ability to manipulate matter at a quantum level makes him extremely powerful. And then there's Galactus, a cosmic entity who devours planets for sustenance.
Vampires are very famous, like Dracula. He has been a staple in fictional horror for a long time. Another is the elves in J.R.R. Tolkien's Middle - earth stories. They are known for their immortality, grace, and wisdom.
Since it's a fan - made concept in a fanfiction, the 9 beings could be anything. They might be nine reincarnations of past powerful ninjas, or nine entities that are manifestations of different elements in the Naruto universe. For example, one could be a being of fire, another of water, and so on. They could also be nine characters with unique kekkei genkai that are united for a special mission or quest within the fanfiction's plot.
Well, it's a really tough call. But some might say Goku from Dragon Ball is the strongest. He has the ability to reach extremely high power levels through intense training and various transformations. His Saiyan blood gives him an edge, and he has fought against some of the most powerful foes in his universe and come out on top. Plus, his Kamehameha wave is a very iconic and powerful attack.
Omnipotent beings in fiction can take various forms. There are the more traditional divine - like entities, like the Greek god Zeus in some retellings of Greek mythology - based fictions. He has the power over lightning, can change his form, and has dominion over the other gods to a certain extent. Then there are more abstract omnipotent beings. In some science - fiction stories, an all - encompassing energy or force might be considered omnipotent, which affects the entire universe and everything in it.
Drogon from 'Game of Thrones' is a very strong dragon. He grew to an enormous size and his fire was extremely hot and destructive. He was a key factor in battles and could easily take on large numbers of enemies.
Another strong robot is Gort from 'The Day the Earth Stood Still'. Gort has incredible power, being able to disintegrate weapons and is highly resistant to attacks. It is a menacing and powerful presence in the movie.