1) The Unseen Elder from The Witcher 3: In the Witcher universe, there are two types of vampires: Lesser and Higher. Even Lesser vampires are a major threat for humans, and Higher vampires can be killed only by another Higher vampire, and they are astoundingly powerful. 

In one point in the DLC *Blood and Wine*, Geralt, accompanied by Regis (a higher vampire), meets the Unseen Elder. The Unseen Elder simply paralyzes Regis with a thought, and if Geralt doesn't answer his questions satisfactorily, he kills Geralt so swiftly that Geralt can't even process wtf just happened before bleeding to death.

2) Gaunter O'Dimm: Again in The Witcher 3, in the *Hearts of Stone* DLC, we meet Gaunter O'Dimm. We have no idea who or what he is, and throughout the story, he demonstrates absolutely OP powers, like casually stopping time (which is so far out of left field as there are not many truly godlike beings in the Witcher universe). Geralt fights him at the end but it's not a conventional fight (more of a metaphysical one), and even though Geralt beats him, it's made very clear that this is just a temporary setback for O'Dimm and he'll return. There are even fan theories that **G**aunter **O**'**D**imm is actually THE God.

3) Reapers from Mass Effect video game series: In Mass Effect, Reapers are galactic janitors who scour the entire galaxy of life the moment a civilization invents self-conscious AI. We practically spend the entire trilogy of games trying find a way to fight back against them, and even when we unify almost every single race in the galaxy against them, it takes a Deus Ex Machina to even beat them. Except in a few situations, our protagonist and their crew immediately retreats the moment they see a Reaper as they have no chance of beating even one of them.

4) Surtr from *Thor*: *Ragnarok*: Surtr is prophesied to destroy Asgard, which he does after being transformed into its true form. Even Hela, the main antagonist of the movie who is shown to be way more powerful than Thor, and who, at that point in the movie, the strongest she has ever been, can't do any real damage to him. Thor doesn't even consider fighting him, and knows that this is a foe he has no chance of beating and immediately retreats.

[Loved Trope] An enemy that is so far above the protagonist's level (bonus points if the protagonist can't even fight it)