It’s a dwarf!
It’s a gnome!
OHMIGOD! 
It’s a Magic Munchkin
by Michael Kolakowski

FREQUENCY:
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ARMOR CLASS:
MOVE:
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% IN LAIR:
TREASURE TYPE:
NO. OF ATTACKS:
DAMAGE/ATTACK:
SPECIAL ATTACKS:
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MAGIC RESISTANCE:
INTELLIGENCE:
ALIGNMENT:
SIZE:
PSIONIC ABILITY:

Munchkins (chuckle). Big deal, they’re the cute little fellers in the
Wizard of Oz, right? Well, my munchkins are somewhat different. My
munchkins are chaotic in the full and true sense of the word; it’s almost
impossible for anyone (except the DM) to figure out what they’ll do
next. The one thing you can always count on a munchkin to do is stay
and bring more munchkins. Munchkins are permanent pests; they are
immune to most magic, and are regenerative. So when you see a
munchkin, assume it’ll be with you for a long time.

Munchkins live in a matriarchal society, in clans ranging from 3-12
in number, with one Munchkin Mother per clan. The mother is about
four feet in height, with the offspring ranging from three to four feet
tall. There is rarely a male parent to be found (5% chance), as the male
leaves not long after mating. The offspring are predominately male
(75% chance each), but males often die upon reaching adulthood, so
there are actually more female adults than males.

As said before, munchkins are permanent pests. They prefer to
sleep in the rubbish pile, so it is advised that this be made as far from
the camp as possible. The munchkins enjoy sorting the garbage, and
playing with it. Don’t try sneaking away, however, as they have remarkable
hearing and smelling abilities. There is a 5% chance per week
(cumulative) that they will leave if ignored, out of boredom. Don’t
count on it, though, as bored munchkins can be quite troublesome.
Bored munchkins have set fire to thieves, and jumped on fighters
shoulders and banged on their helms.

Some munchkins are different than the others, however. These
dreaded Magic Munchkins (10% chance of 1 per 25) are exactly like
their normal (?) cousins, except that they can use one magic spell per
day (up to and including 9th level, as an eighteenth level Wizard). The
Munchkin Mother can do three spells per day.

Munchkins tend to be rather stupid, as well as moderately weak
(but persistent). They can’t be fought in any ordinary fashion, nor do
they fight. It is possible to escape normal munchkins by flying or
teleporting, but this will not work against the magic variety. The only
way to kill a munchkin is with a special weapon such as a Sword of
Munchkin Slaying (automatically kills upon scoring a hit). Some magic
items can detect approaching munchkins. Even the most ancient of
magic items sometimes can; they’ve been around for quite some time.

Note! Munchkins should not be employed in normal dungeon
expeditions; they should be used when all the characters are high-level
types who are easily bored, or with hot-shots who think they know it
all.
 
Dragon magazine MM - The Dragon #17 1st Edition AD&D