Ghost

ghost
Difficulty	12
Attacks	Touch 1d1

ghost
Difficulty	12
Attacks	Touch 1d1
Base level	10
Base experience	220
Speed	3
Base AC	-5
Base MR	50
Alignment	-5 (chaotic)
Frequency (by normal means)	Not randomly generated
Genocidable	No
Weight	1450
Nutritional value	0
Size	Medium
Resistances	Cold, Disintegration, Sleep, Poison, Stoning
Resistances conveyed	None
A ghost: can fly. can phase through walls. does not breathe. has a head, a couple of arms, and a torso. does not have a solid form. does not eat. (*) is not a valid polymorphable form. is undead. is normally generated hostile. can follow you to other levels. has infravision. never leaves a corpse.
Reference	monst.c#line2515

A ghost is a type of monster in NetHack. Ghosts are most likely to appear as copies of previous-dead players in bones files, complete with their whole object assortment, and the pet may be nearby (feral). Any objects that were carried in the unfortunate player's main inventory have an 80% chance of being cursed; other objects on the level and the contents of containers in the player's inventory maintain their BUC status.

Ghosts will also appear in graveyards and in haunted temples.

Quaffing a milky potion may cause a ghost to appear.

Ghosts are VERY slow and do very little damage. However, they will probably evade all your hits if you meet them on a low level. If you can't kill them fast via regular attack, try kicking them instead.

Encyclopedia entry

And now the souls of the dead who had gone below came swarming
up from Erebus -- fresh brides, unmarried youths, old men
with life's long suffering behind them, tender young girls
still nursing this first anguish in their hearts, and a great
throng of warriors killed in battle, their spear-wounds gaping
yet and all their armour stained with blood.  From this
multitude of souls, as they fluttered to and fro by the
trench, there came a moaning that was horrible to hear.
Panic drained the blood from my cheeks.
    [ The Odyssey, (chapter Lambda), by Homer ]