What power level are you thinking of, or is it varied?
Big jump in power level from some street-level vigilantes (e.g., Marvel's Defenders) to cosmic fighters like Superman.

If it's going to be inconsistent -- which is fine, if unfair for the guy fighting Superman -- there were a few threads about brainstorming superheros or villains. I tried a couple searches but didn't find them, but maybe you'll have better luck. You could also look at the list of characters in the web serial Worm and draw from there.