# Monster class
All monsters belong to a monster class, based on the default ASCII monster symbol that represents them. For some classes, such as x or w, the symbol is almost all that unites them. Other symbols represent monsters that share much in common, such as D or K. Additionally, some classes have individual members that are in many ways an "odd one out", such as E&nbsp;stalkers and e&nbsp;gas spores.
A blessed scroll of genocide allows you to wipe out some or all the species of a certain class. You can change the appearance of each class with the monsters option (3.4.3) or with custom map symbols (3.6.0+). A common change is to display ghosts and shades as X or 8 instead of &nbsp; to make them more visible. However, this has no effect on the behaviour of genocide.
These descriptions are given in the game when you examine monsters with the far look ; or what is / commands.[1][2] Some of the in-game descriptions are incomplete; extra information is italicized.

a, ant or other insect
b, blob
c, cockatrice (or pyrolisk)
d, dog or other canine
e, eyes or sphere
f, cat or other feline
g, gremlin (or gargoyle)
h, humanoid
i, imp or minor demon
j, jelly
k, kobold
l, leprechaun
m, mimic
n, nymph
o, orc (including goblins and hobgoblins)
p, piercer
q, quadruped
r, rodent
s, arachnid or centipede
t, trapper or lurker above
u, unicorn or horse
v, vortex
w, worm
x, xan or other mythical/fantastic insect
y, light
z, zruty
A, angelic being
B, bat or bird
C, centaur
D, dragon
E, elemental (or stalker)
F, fungus or mold
G, gnome
H, giant humanoid
J, jabberwock
K, Keystone Kop
L, lich
M, mummy
N, naga
O, ogre
P, pudding or ooze
Q, quantum mechanic
R, rust monster or disenchanter
S, snake
T, troll
U, umber hulk
V, vampire
W, wraith
X, xorn
Y, apelike creature
Z, zombie
@, human or elf
&nbsp;, ghost (or shade)
', golem
&amp;, major demon

;, sea monster

:, lizard
The farlook (;) and whatis (/) commands also show the following symbols, which are not monster classes:

I, the remembered location of an unseen creature
~, part of the tail of a long worm
], one of the appearances of a mimic, described by farlook as "a strange object".
References

↑ drawing.c in NetHack 3.4.3, line 160: Monster descriptions

↑ monsym.h in NetHack 3.4.3, line 81: Default characters for monster classes

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It may contain text specific to NetHack 3.4.3. Information on this page may be out of date.
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