->''"My name is Don Simon Xavier Christian Morado de la Cadena-Ysidro, and I am what you call a vampire."''

''Those Who Hunt the Night'' (1988, also published as ''Immortal Blood'') is a HistoricalFantasy novel by Creator/BarbaraHambly. Professor James Asher, Oxford linguist and retired spy, is unwillingly recruited by the vampires of London to track down a hunter who is killing them one by one. He sets to work, with the assistance of his wife Lydia, a physician, and Don Simon Ysidro, a former Spanish nobleman who has been unliving in London since the days of UsefulNotes/ElizabethI.

Has several sequels: ''Traveling with the Dead'' (1995), ''Blood Maidens'' (2011), ''Magistrates of Hell'' (2013), ''Kindred of the Dead'' (2014), and ''Darkness on His Bones'' (2015).

!!This series provides examples of:

* BloodyMurder: In ''Those Who Hunt the Night'', a character kills a vampire by injecting himself with a lethal dose of silver nitrate (silver being fatal to vampires in this setting) and allowing the vampire to drain him before he succumbed to the toxic effects of the silver nitrate.
* {{Deconstruction}}: Lydia's plot strand in ''Traveling with the Dead'' is a merciless deconstruction of Vampire Romance.
* DirtyBusiness: James Asher's experiences working for the English secret service.
* IGaveMyWord: In ''Blood Maidens'', a vampire master informs fledglings that he has promised Asher his protection, and dreadful things will happen if anyone hurts him.
* MarketBasedTitle: ''Immortal Blood'' (''Those Who Hunt The Night'')
* TheMirrorShowsYourTrueSelf: Hambly's vampires avoid mirrors not because they lack reflections, but because their reflections show what they are instead of what their glamours make them appear (even to themselves) to be.
* NobleDemon: Don Simon Ysidro, despite being a vampire, has a distinctive sense of honor due to his nobility (''noblesse oblige'').
* TheOlderImmortal: [[spoiler:Brother Anthony the minorite, over 400 years old, makes Grippen and Ysidro seem like callow youths.]]
* OurVampiresAreDifferent: Vampires grow slowly more resistant to their banes (silver, certain woods, sunlight) as they age past their "death". This comes with occasional side effects: Don Simon Ysidro and his sire Rhys developed a condition called bleaching, where they turned into near-albinos, and the Bey of Constantinople became unable to fully create new vampires -- attempts simply produced a functioning mind in a rotting body. They're also psychic, able to affect people's minds -- the famed "dissolve into mist" act is just mentally blanking a person's ability to focus on them, and since they feed on the psychic energies of their prey's death-by-bite, they cannot feed without killing. They all cast psychic glamours that improve their appearance -- even the ones that aren't vain about their appearance prefer to at least seem ''alive'', which without the glamour it's immediately obvious they're not. They avoid mirrors not because they aren't reflected, but because they are, and the mirror shows their true unglamourous appearance.
* PerceptionFilter: When vampires seem to appear or disappear, it's really a psychic perception filter causing the observer to be distracted at the crucial moment.
* ShoutOut: At one point, the subject of ''Literature/{{Dracula}}'' comes up; Don Simon and his fellow vampires are aware of it, and amused by the way Stoker clearly thinks of England as being vampire-free before Dracula's arrival.
* StrongerWithAge: Vampires grow tougher as they age, eventually becoming resistant to their weaknesses -- an ancient vampire can withstand the touch of silver that would burn and sicken a fledgling (newly created vampire) with even the slightest contact and even resist the light of the sun and the irresistible sleep that forces all younger vampires into a coma during the daytime hours. Their psychic powers (and presumably physical strength) also increase with age, although there are also possible, though inconsistant, degredations with age.
* TalkingInYourDreams: Hambly's vampires can communicate with people's dreams.
* TearsOfRemorse: In ''Blood Maidens'', Lydia remembers how a companion died, feels guilt, and tears start to her eyes.