Re: In your Universe ...
I have a few settings so it varies.
For example, in the Redwood Academy setting many heroic figures that are fictional or who's abilities are made superhuman in tall tales in our world existed (Robin Hood, Hercules, John Henry) existed and their legendary abilities were examples of powers
In the Wyldstrike universe that's not generally the case though some more modern celebrities have developed powers either as mutants, being caught in the Wyldstrike or purchasing them somehow (usually to stay relevant in a celebrity sphere increasingly dominated by superhumans). For example, Paris Hilton is a mutant with enhanced intellect and something of a demonologist/occultist (the paranormal is current "in" among the upper crust).