From my notebook of OD&D house rules:
A 4th level Fighter is a Hero indeed, an adventurer worthy of a bard's praise. Veterans of many wars may never reach such lofty heights. In fact, nearly all people encountered will be Normal Men and Normal Women of 1 Hit Die and no levels, including many knights and hereditary nobles.
Similarly, most of the clergy at the various temples are Normal. In the safeties of civilization some so-called Patriarchs may be nothing more than Normal Man ecclesiastical bureaucrats. The ability to Turn Undead is generally considered a sign to expect great things from a young acolyte.
Even the Magic-User Guild has its share of Normal type people, forming a body of almost-apprentices who work as assistants to various higher grade MU's. About 1 in 6 such assistants have some minor skill with spells. See below.
1) Can cast a first level spell per week.
2) Can cast a first level spell per month.
3) Can cast a single first level spell once per day. (E.g. only understands a single spell)
4) Can Overcast 1/day as MU2 but -2 to the overcast roll.
5) Can write scrolls twice as slowly as an MU1.
6) May research spells at double cost or assist others in such research.
The basic deal is that in my low-level oriented setting having even one level in an adventuring class is a Big Honkin' Deal. The town guards? Almost assuredly Normal Men. The king's vizier? He may not be a wizard, but instead just a really clever dude with one hit die.
The last three items on the d6 chart for assistant magic-users were written under an earlier draft of my house rules for MUs and don't make a lot of sense outside that context. Still, I think you can get the general idea.
Monster Manual Unwrapped
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