Vampire (monster class)
The monster class contains the following monsters:
Vampires are chaotic human undead - they are strong, breathless, capable of flying and regeneration, and possess sleep resistance and poison resistance. All vampires are vulnerable to silver weapons, possess a characteristic life-draining bite, and will follow you to other levels if on an adjacent square.
Vampires are shapeshifters and can polymorph at will into vampire bats or fog clouds - vampire lords and Vlad the Impaler can additionally shapeshift into wolves. Vampires often turn into their animal forms when outside of the player's sight, and shift into fog cloud form to flow under locked or inaccessible doors - vampires will also shift to their other forms while healthy, and shift back to their base form if their HP is low enough. Polymorphing a vampire will cause them to take on one of their other forms rather than become a new monster, unless they became a vampire via polymorphitis. If killed in any of their shifted forms, including by stoning, they will resurrect in vampire form. Vlad the Impaler will not shapeshift if he is carrying the Candelabrum of Invocation.
Non-unique vampires are among the various undead that can generate in graveyards.
In addition to hosting graveyards, the following levels also generate random V on level creation:
- Three random types of vampire are generated in the Valley of the Dead.
- Three random vampires appear within the left inner chambers of Asmodeus' Lair.
- Six random vampires rest behind hidden doors within Vlad's Tower.
- Three random vampires are also generated in Moloch's Sanctum.
- Three random vampires appear on the Astral Plane.
Vampires are considered corpseless, with a special case that causes any non-unique vampire to leave a tainted human corpse upon death - reviving that corpse will resurrect the vampire. Human characters killed by a member of the vampire class will arise as a vampire instead of a ghost in any bones file that is created.
As a polymorph form
Players in the form of any vampire will "scrawl in blood" rather than "write in the dust" when engraving; they are also warned of any human or elf, and will turn into vampire bats if they polymorph again or use the #monster extended command - they can decline to do so if they have polymorph control.
Vampires often make for annoying fights, since their bites can rob you of experience levels unless you have drain resistance, e.g. from an artifact weapon like Excalibur; MC3 is the next best option in the event you lack this resistance. Vlad the Impaler is the worst offender by far, due to his high speed and covetous behavior.
Vampires represent a tempting target for a blessed scroll of genocide - though not as vicious as mind flayers or arch-liches, vampire lords in particular can still be troublesome; if you are early enough in the game, you may consider doing so in order to increase the amount of wraiths generated in graveyards.
Vampires are decently strong as pets, with vampire lords being significantly popular choices - vampires need only two levels to grow up into vampire lords. However, pet vampires will shapeshift as normal unless you are wearing a ring of protection from shape changers - in their other forms, they are weak fighters that cannot wear armor, and will break body armor if they shift into wolves. A tame vampire will not shapeshift back to humanoid form unless killed or forced back to normal by the ring of protection from shapechangers - players planning to keep vampire pets should identify this ring as soon as possible.
Vampires' huamnoid forms are their strongest by far, with good base AC and access to all armor giving them the potential for high survivability. However, their silver weakness and lack of elemental resistances can easily work against them.
As a polyform
Both available vampire forms are good for players with polymorph control - they can wear armor and wield non-silver weapons, and their regeneration, flight, breathlessness, and lack of hunger are all unambiguous boons. The vampire lord is a strictly better choice in all respects, with slightly more AC and speed. The vampires' silver weakness is just as much a danger to you as it is to other vampires, however, and you will need to avoid engaging certain monsters such as cockatrices in melee.
The base vampire first appears in Hack 1.21, a variant of Jay Fenlason's Hack; in this, PDP-11 Hack, and Hack 1.0, the vampire uses the V glyph. The vampire lord and Vlad the Impaler first appear in NetHack 3.0.0, while the vampire mage's deferred data can be found in the source code as early as NetHack 3.3.0.
In 3.4.3 and some previous versions, including some variants based on those versions, vampires were often used in drain for gain strategies and were thus a prevalent choice for abusing the polyself bug, to the point that they were specifically mentioned in the bug's official description. The "drain for gain" strategy was adjusted in NetHack 3.6.0, and the polyself bug was fixed.
Vampires' shapeshifting abilities were added in 3.6.0; this makes them somewhat better pets in previous versions and some variants based on them, as they will not shapeshift out of any armor you give them. There are two related bugs to this, both fixed in NetHack 3.6.1:
- Genociding vampires and/or vampire lords would caused currently shapeshifted ones to become unkillable, as they could not return to vampire form properly. This was fixed in commit 757e6f9.
- Shapeshifters such as chameleons and other monsters that polymorphed into vampires would remain stuck in that form - e.g., shapeshifters would not take on new forms, a polymorph-produced vampire would not shift to bat or fog forms, and so on. This was fixed in commit 885de11 and commit 45ba0ad.
For the purpose of these messages, a vampire regards you as "kindred" if you are in the form of a vampire yourself, and considers you a "night child" if you are in the form of a wolf (including winter wolves and their cubs).
The following five messages occur if you chat to a tame vampire in its humanoid form:
- Good evening to you Master!
- You are kindred, and it is night.
- Good day to you Master. Why do we not rest?
- You are kindred, and it is day.
- <Child of the night,> I can stand this craving no longer!
- It is midnight, with the prefixed message occurring if you are in wolf form.
- <Child of the night,> I beg you, help me satisfy this growing craving!
- As above during the night, but it is not midnight.
- <Child of the night,> I find myself growing a little weary.
- As above, but it is day.
These messages occur if you chat to a peaceful vampire:
- Good feeding <brother/sister>!
- You are kindred, and it is night.
- How nice to hear you, child of the night!
- You are a night child, and it is night.
- I only drink... potions.
- You are neither kindred nor a night child, or it is day time.
These messages occur when chatting to a hostile vampire:
- This is my hunting ground that you dare to prowl!
- You are kindred.
- <Young> Fool! Your silver sheen does not frighten me!
- You are polymorphed into a silver dragon; "Young" is appended if you are polymorphed into a baby silver dragon.
For chatting to hostile vampires in other forms, one of the two following sets of messages is randomly chosen, with the first set depending on your body parts:
- I vant to suck your life force!
- You are polymorphed into a sphere or vortex.
- I vant to suck your juices!
- You are polymorphed into a jelly or fungus.
- I vant to suck your blood!
- You are in a form that is not any of the above.
Otherwise, their response is one of the following:
- I vill come after a <man/woman> without regret!
- You are a human. 
- I vill come after a <race> without regret!
- You are polymorphed or naturally non-human.
Many variants add the vampire as a playable race and add the deferred vampire mage, often alongside other members.
Vampires are a starting race added in SLASH'EM - this means that Doppelgangers cannot polymorph into vampires, though they can still polymorph into any other member of the vampire monster class. In addition, there are four new vampires added to the monster class:
- V Vampire mage, a spellcaster who notably has access to the summon nasties spell on top of three attack per turn, including a stronger claw and bite that can drain levels.
- V Fire vampire, which is a Lovecraftian alien rather than undead, though it shares the vampiric weakness to silver. Fire vampires can use unreflectable fireball attacks, move twice as fast as a normal hero, and have five attacks per turn, including fiery touches.
- V Star vampire, which is another extraterrestrial from Lovecraft's works, and similarly weak to silver. They lack the fire vampire's speed and any elemental affinity, but can attack six times per turn with three drain life attacks mixed in.
- V Count Dracula, the Undead Slayer quest nemesis and another monster based on the 1897 Bram Stoker novel Dracula.
Eight random vampires will be generated on the Chaotic Quest at level creation.
Most vampires hits monsters as +x weapons: base vampires hit as +2, Count Dracula hits as +4, and all other V hit as +3. Base vampires also require a +2 weapon to be hit, while every other vampire except Count Dracula requires a +3 weapon. Tamed vampires are now traitorous and have a change to turn on you, making them possibly perilous choices for pets while at lower levels.
Undead vampires are often generated with opera cloaks and can provide a valuable method of farming them, especially if they are randomized into the cloak of magic resistance; the tradeoff is the vampires in question being harder to dispatch depending on the cloak, particularly vampire mages. Elemental spells are good substitutes for the usual magic missile in such scenarios, especially the acid stream spell.
The wooden stake is a dagger-type weapon that does 1d6 extra damage to any vampire, on top of an additional +2 damage and a 10% chance of instakilling them if the wielder is an Undead Slayer, has Expert skill in dagger, or is using The Stake of Van Helsing.
Player vampires and players polymorphed into undead vampires can fly and do not need to breathe, but they cannot eat solid food and have to rely on fresh blood as a food source. SLASH'EM adds the potion of blood and potion of vampire blood as nutritional replacements for vampires: Player vampires receive potions of vampire blood in place of the food other monsters would start with, and can use the draw blood technique to create one by draining one of their levels; undead vampires in the dungeon may generate with either potion. Non-player vampires of any kind will drink non-cursed vampire blood to restore 2-10 HP, and gain nothing from drinking cursed potions. Player vampires gain 20 nutrition from an uncursed potion of blood and 30 from a blessed one; an uncursed potion of vampire blood grants 800 nutrition points (400 if diluted), and a blessed potion additionally increases your HP and max HP by the same amount as a level gain.
A non-vampire player that attempts to drink a potion of blood will be given 10d8 (more) turns of nausea. A non-vampire drinking vampire blood will instead polymorph into a vampire. Non-vampires also suffer a −3 alignment penalty if neutral, while lawfuls and Monks take a −15 alignment penalty and anger their god. The polymorph is "semi-permanent" and will last until your HP is reduced to 0.
Vampires may also get nutrition from combat using their bite attack in combat, and can drain blood from corpses. A corpse that is left alone too long will have its blood coagulate, rendering it useless as a nutrition source. While blood consumed in this manner provides a very small nutritional value, the drained corpses are still eligible for sacrifice, reducing the need to weigh staying full against sacrificing. As vampires are human undead, the usual penalties apply for draining other humans, as well as dogs and cats.
As with SLASH'EM, UnNetHack also adds the vampire as a starting race, and randomly generated vampires are also often generated with opera cloaks. The same conditions for player and polyself vampires apply as in SLASH'EM, as do the conditions for vampires generating with potions of blood.
A non-vampire drinking vampire blood will polymorph into a vampiric monster depending on the potion's beatitude - blessed potions will polymorph them into a vampire lord; an uncursed potion will turn them into a vampire, as in SLASH'EM; and a cursed potion will morph them into a vampire bat. The same penalties for non-chaotic characters apply.
In dNetHack, vampires are also a starting race. Pet vampires will drain corpses for nutrition the same way a player vampire does, with similar conditions (i.e. corpses must be less than 3 turns of age and have blood).
Vampires appear among the undead that make up 1⁄7 of randomly-generated monsters on the Anachrononaut quest - 3⁄4 of the undead monsters generated randomly will be from the vampire monster class.
In addition to SLASH'EM details, SlashTHEM adds the following vampires:
None of the new vampires that can be tamed are capable of treachery.
- include/monsym.h in NetHack 3.6.7, line 62
- src/monst.c in NetHack 3.6.7, line 1843
- src/mon.c in NetHack 3.6.7, line 3385
- src/mon.c in NetHack 3.6.7, line 3379
- src/mon.c in NetHack 3.6.7, line 3340
- src/mon.c in NetHack 3.6.7, line 3327
- src/mon.c in NetHack 3.6.7, line 3849
- src/mon.c in NetHack 3.6.7, line 2190:
if (!vamp_stone(mdef))is used to exclude shifted vampires from instant death by stoning
- src/mon.c in NetHack 3.6.7, line 3375: If he does not have the Candelabrum, Vlad falls through to the vampire lord case
- src/monmove.c in NetHack 3.6.7, line 154
- src/mon.c in NetHack 3.6.7, line 171
- src/mon.c in NetHack 3.6.7, line 354
- src/end.c in NetHack 3.6.7, line 517
- This quote comes from the 1994 film Ed Wood, but is commonly mis-attributed to Bela Lugosi's titular character in the 1931 Dracula.
- This "famous vampire quote" appears to be an oblique allusion to the 1994 film Interview with the Vampire: The Vampire Chronicles, as determined by this RGRN discussion regarding Vlad.