An ancient naga, N, is a type of monster that appears in dNetHack. It is a multi-headed naga that possesses fire resistance, shock resistance and stoning resistance alongside the usual poison resistance. Ancient nagas are the only member of their monster class to be humanoid and possess functional arms: this makes them capable of wearing all armor fitted to their size except for boots, where most nagas in dNetHack can only wear mail and helms.
Ancient nagas have four attacks: two weapon attacks, a powerful bearhug, and a poisonous bite attack that occurs each global turn and targets either 5 or 7 adjacent monsters that the naga is hostile towards, depending on the number of heads it has.
Ancient nagas are a fearsome enemy to face in melee due to their 18 speed and bearhug attack, which can deal up to 80 on its own; their stellar effective base AC of -10 also makes them fairly difficult to hit.
As a polyform
The ancient naga is among the more powerful polyself forms available to a player: they have similar anatomy to a salamander, allowing them to wear all huge-sized body armor minus boots, and their two weapon attacks and bearhug allow for very high damage output while the automatic bite attacks can clear away weaker enemies. However, a significant drawback is that the form is too large for standard-sized armor: players looking to use the polyform long term will need to remove their armor before transforming, then use an upgrade kit to resize it all to fit them.
The Nāga (feminine "Nagi") are creatures that appear in Dungeons & Dragons, and are based on a supernatural race of half-human half-serpent beings that originate in the folkloric traditions of many South Asian and Southeast Asian cultures; Nāga have held cultural significance in these cultures over the past two millennia. They can occasionally take human form, and their most common depiction is that of a snake with a human head, which the default tiles of NetHack draw from—other iconographic depictions portray them as human from the waist up and snake from the waist down, wholly human with snakes on the heads and necks, or even as common serpents.
Nāgas are also portrayed as having multiple usually-serpentine heads - the ancient naga of dNetHack is based on the various multi-headed interpretations, as their passive bite is flavored as coming from its multiple cobra heads. One notable naga of this type is King Mucalinda, who appears in the Vinaya Sutra and shelters the Buddha from a great storm by covering the Buddha's head with his seven snake heads.