Elminster
Elminster is an old-ass wizard from Forgotten Realms, oft-cited as one of the main reasons why that setting sucks shit. He's powerful enough to solve any problem that would challenge PCs, and no real reason not to do so which isn't utterly contrived. He's an Urza figure without the apathy or plane-ruining fuckups. Oh, and he's also Ed Greenwood's self-insert, the original Mary Sue of Faerûn from before Drizzt was a thing.
He's slept with more women than Greenwood ever will, including the goddess of Magic. Just because. Dude's left so many single moms and orphans around that one of the novels is about one of his abandoned daughters robbing his home, and he lures her in to be used as a pawn in fighting a conspiracy of wizards. What a dick.
Reason why Elminster doesn't do crap
There is a reason that is explained in the novels of why he doesn't kill every badass evil wizard and that is mainly the collateral damage.
Imagine two epic level wizards duking it out in your region odds are the entire region is going to go pits up and be quite a bit of a damaged wasteland for quite awhile. It would most likely be the equivalent of a nuclear bomb going off.
So ya there is a reason that he doesnt man up and go after every BBEG in the setting. But then again there are more BBEG in Forgotten Realms than their is good wizards so let that sink in for you.