Rediscovering the level range for the H4 -
Throne of Bloodstone module (AD&D1) -- for levels 18-100 -- prompts me to ask this question:
What's the highest level character you've ever played in any edition of D&D? A character you played for at least one game session.
What's the highest level you've ever heard of someone playing in any edition of D&D?
Bullgrit
Total Bullgrit
Edena, 161st level (in Storybook Terms, 35th level, or on a par with Ioulaum of Netheril, except as a cleric, not a wizard.) (My SN is based on this character.)
You could say that Waldorf was the highest level I've ever heard of being fully played out as a character, but it is unclear what his level really was. Since he enslaved all the Gods of Oerth (the Greyhawk Campaign Setting) and put them to work in the mines under his castle, he must have been pretty high level.
Waldorf was finally killed when someone rammed a Spelljamming at near light speed into that castle, and the Spelljammer was filled with nilbogs. The controls that slow a Spelljammer down prior to planetfall had somehow been overridden.
This was from Dragon Magazine, and others can expound on this.
The highest level Player Character I ever saw played with my own eyes was a wizard of 75th level named Soloron.
This character was quite memorial, in that he created the first Wizard Army I had yet seen in fantasy roleplaying, and attempted to conquer the Greyhawk Setting with them. And he did conquer about half of it. He might have conquered all of it, but his opponent, Alderan (the Grandmaster of Assassins, 15th level) stopped him.
Soloron operated out of the mountains north of the Black Ice, where the City of the Gods might have been (except they put it on Mystara instead.) His great castle was there, complete with deathtraps that would have humbled Acererak (or made him royally angry, since Acererak considered himself the One and Only at that time.)
So, what beat Soloron? Ear wigs (yes, ear wigs. Those things were much nastier than anyone ever gave them credit for being.)
The most powerful NPC I ever saw played, personally, was a 750th level wizard.
I do not know her exact stats, her range of spells, or her special abilities.
I never saw her in actual combat. Believe it or not, the time I saw her, she was in the midst of a diplomatic session.
I never learned what happened to her, if anything.