Watcher in the Water
The Watcher comes from the first part of The Lord of the Rings: The Fellowship of the Ring. It appears as a mysterious aquatic creature lurking in a pool outside the western entrance to the dwarvish realm of Moria, from which it attacks the main characters (the Fellowship) as they are about to enter. The encyclopedia entry describes the creature as it grabs Frodo, the protagonist, and tries to drag him underwater. The name "The Watcher in the Water" comes from a historical account the party discover later, which reveals that the monster also prevented Moria's defenders from escaping through that exit.
Little is known about the exact nature of the creature, as the characters catch only a brief glimpse of it, but the detail of its having tentacles (at least twenty) suggests that it may be some kind of monstrous cephalopod. The passage describes the Watcher's tentacle as "fingered", which is inconsistent with real-life cephalopods, but this may simply be a metaphor meaning that the tentacle was curled like a finger.
In vanilla NetHack and SLASH'EM, the passage describing the Watcher is used as the encyclopedia entry for the kraken, implying that (in those variants at least) the Watcher is assumed to be representative of that legendary creature, which is usually portrayed as a giant cephalopod. (UnNetHack changes the kraken's encyclopedia entry to an unrelated poem by Alfred, Lord Tennyson.) In the variants that include the Watcher, it shares the kraken's drowning attack, but may have distinct attacks of its own.
In both UnNetHack and dNetHack, the Watcher appears as a "boss" at the surface end of a series of levels inspired by Moria.
The Watcher can be teleported onto dry land to make it less dangerous. Killing it over land also ensures that its magic lamp can be retrieved.
Out from the water a long sinuous tentacle had crawled; it
was pale-green and luminous and wet. Its fingered end had
hold of Frodo's foot, and was dragging him into the water.
Sam on his knees was now slashing at it with a knife. The
arm let go of Frodo, and Sam pulled him away, crying out
for help. Twenty other arms came rippling out. The dark
water boiled, and there was a hideous stench.
The Watcher is the 'mid boss' of the dwarf noble (Dnb) quest. The main body of the Watcher attempts to remain at least 3 squares from the character at all times, and attempts to avoid being on the same line in order to frustrate ranged attacks. The main body will spawn tentacles with its gaze attack; up to a maximum of 6 swarms of snaking tentacles and 2 long sinuous tentacles will be generated. If the Watcher's main body is killed, all the tentacles die as well.
swarm of snaking tentacles
Swarms of snaking tentacles are generated by the Watcher in the Water, and will attempt to drown the player character. No more than 6 swarms will be generated at a time; however, destroyed tentacle swarms will be replaced by the Watcher's main body.
long sinuous tentacle
Long sinuous tentacles are generated by the Watcher in the Water. They do not have a drowning attack; however, they have a strong two-square reach attack. No more than 2 of these tentacles will be generated at a time, destroyed tentacles will be replaced by the Watcher's main body.