While related by symbol to the ape and carnivorous ape, the monkey is quite different. Unlike its larger cousins, the monkey is very weak. What it lacks in ferocity, however, it makes up for with mischievousness. The monkey will, before attacking, steal a random item from the adventurer, then immediately flee, attempting to make off with the player's property. Monkeys are not particularly fast and don't teleport like nymphs do, so it's usually not too difficult to chase them down and kill them. (If you're a Knight, keep in mind attacking a fleeing monster incurs a small alignment penalty.)
Monkeys cannot steal worn items that are cursed.
"Listen, man-cub," said the Bear, and his voice rumbled like
thunder on a hot night. "I have taught thee all the Law of
the Jungle for all the peoples of the jungle--except the
Monkey-Folk who live in the trees. They have no law. They
are outcasts. They have no speech of their own, but use the
stolen words which they overhear when they listen, and peep,
and wait up above in the branches. Their way is not our way.
They are without leaders. They have no remembrance. They
boast and chatter and pretend that they are a great people
about to do great affairs in the jungle, but the falling of
a nut turns their minds to laughter and all is forgotten.
We of the jungle have no dealings with them. We do not drink
where the monkeys drink; we do not go where the monkeys go;
we do not hunt where they hunt; we do not die where they die...."