Head of the CDC's rapid-response team, the Canary Project, Eph is a newly divorced father attempting to balance the custody battle over his son Zack with his duties as an epidemiologist. He and his Canary team are first-responders to the Boeing 777 disaster, and are tasked with solving the mystery of the mass casualty.
- Anti-Hero: Starts out as a Type I in the first book, where he's still coming to grips with the vampire plague, and is still somewhat bitter. By The Fall, he's a hardened Type IV, being off the wagon and much more violent and impulsive, but is still doing everything in his power to defeat the Master. In The Night Eternal, he has fallen into a Type V, now a drug addict in addition to an alcoholic, and is willing to doom the entire human race just to save Zack, who he never even had a chance of saving.
- Broken Pedestal: Increasingly so to Zack. Over the course of the two years between the second and third books, Zack grows to resent him for trying to kill Kelly, who has been turned, and for his constant absence. After Eph does kill her, Zack announces his hatred to him, although it's implied that they may have improved their relationship if Eph had any choice in the matter.
- FaceHeel Turn: Subverted. He takes the Master's offer to return Zack to him in exchange for the Lumen, into serious consideration, but eventually comes around and realizes that it could only end poorly, no matter the outcome.
- First Father Wins: Kills Matt after he'd been turned.
- Heroic BSoD: Twice. First after he sees Kelly as a vampire, he relapses into alcoholism. And again when Zack is abducted. This drives him deeper into depression and using drugs to cope and remain focused. He even tries to betray his friends by giving the Master the Occido Lumen in exchange for his son. He gets better, though.
- Heroic Sacrifice: Blows up himself and Zack, along with the Master's origin site.
- Knight in Sour Armour: He has good intentions, wanting to stop the vampiric invasion and all that, but he's a pissed-off alcoholic with poor impulse control.
- My God, What Have I Done?: Undergoes this when he realizes that he was wrong to even think of going through with the Master's deal.
- Papa Wolf: Do not. Harm. Zack.
- Redemption Equals Death: Having spent a good portion of the third book in a deep depression and strongly considering the Master's bargain to return Zack to him in exchange for the Lumen, he ultimately decides against it, nuking the Master's origin site, along with himself and the corrupted Zack.
- Took a Level in Jerkass: After relapsing into alcoholism, he becomes a lot more aggressive and cynical, and in The Night Eternal, seriously considers accepting the Master's offer to return Zack to him in exchange for the Occido Lumen, despite knowing full well that doing so would doom humanity, and that he might go back on his word.
Eph's estranged wife and current opponent in a drawn-out custody battle over their only son.
- Aborted Arc: She appears to be ready to reconcile with Eph. This goes nowhere, as she is turned by Matt.
- Mama Bear: She's highly protective of Zack, and she carries this trait over when she's turned, going so far as to lead an army of feelers to the subway train just to get a hold of him.
The young son of Ephraim and Kelly.
- FaceHeel Turn: After the Master feeds him some of his own blood to treat his asthma.
- HeelFace Door-Slam: Only re-acknowledges Eph as his father when it's too late.
- Stockholm Syndrome: The end result of him being fed the Master's blood and spending two years under his care. He grows accustomed to his captivity, and becomes increasingly evil.
- Took a Level in Jerkass: Arguably a milder example than the show, but over the course of the second book, he grows to resent Eph for trying to kill Kelly who had been turned and eventually ends up under the Master's tutelage, killing animals and being groomed to become his new host.
- Wise Beyond Their Years: While still somewhat naïve, Zack is shown to be rather resourceful for his age, for instance, teaching his father how to upload footage to prove the existence of vampires.
Prof. Abraham Setrakian
A Romanian Jew who escaped the Treblinka extermination camp during the Second World War, Professor Setrakian has been a dedicated (and perhaps fanatic) vampire hunter for over six decades.
- Battle Cry: "My sword sings of silver!"
- Cool Old Guy: Notable for being a vampire hunter even to his old age.
- Heroic Sacrifice: Allows the Master unaware of the blood-thinners he took to feed on him, forcing him to possess Bolivar, effectively weakening him.
- Sword Cane: His signature weapon.
A skilled epidemiologist, Nora is second in command of the Canary Project. She and Eph have been attempting an office romance with mixed success, complicated by their high-stress medical careers and Goodweather's lingering melancholy over his looming divorce. Nora quickly dedicates herself to uncovering the vampire conspiracy, and is determined not to be relegated to doing the "woman's work".
- Action Girl: Shows that she's more than competent at dispatching vampires.
- Hospital Hottie: She works for the CDC and is quite attractive. We also get a description of her in her undergarments.
- Pair the Spares: She hooks up with Fet in The Night Eternal, and stays with him after everyone else dies.
- Took a Level in Badass: In The Strain, she sits out the assault on Bolivar's mansion. By The Fall, she's skilled in vampire hunting and manages to wound Kelly.
- Traumatic Haircut: In The Night Eternal, her head is shaved when she's taken into the blood camp.
An exterminator working for the New York City Bureau of Pest Control, Fet's occupation soon leads to his discovering the truth about vampires in a derelict building. Reaching Eph through a professional connection at the CDC, the exterminator lends both his skills as a vermin hunter and his powerful physique to Setrakian and Goodweather's cause.
- The Big Guy: He's described as "filling the doorway".
- Pair the Spares: Hooks up with Nora in The Night Eternal in Eph's absence, and they stay together by the end of the book when everyone else is dead.
The Ancients' chief headhunter, Mr. Quinlan is a massive, enigmatic vampire devoted to eliminating the Master's bloodline. Once the remaining Ancients had been wiped out, he teams up with Setrakian's team to aid them. He's revealed to be the Master's bastard son, transformed by the disease while in his mother's womb and becoming a dhampyr.
- Abusive Parents: The Master sure knows how to make his already-cursed life into a living Hell. He murdered his mother, and then later the wife and child the Ancients gave him, and has been trying to either kill him or corrupt him for the longest time. It's no wonder Quinlan doesn't care whether he "lives" or dies.
- Anti-Hero: Somewhere between Type IV and Type V. On one hand, despite being a ruthless killer, he's completely justified in his actions. On the other, he makes a point to show the heroes that he could very easily betray them.
- Badass Baritone: Described as having one.
- Dark Is Not Evil: Dresses in a black hoodie and is a dhampyr working for the Ancients, but really, all he wants is to destroy the Master and his bloodline, and himself with it.
- Daywalking Vampire: Subverted. Despite being a dhampyr, Quinlan is not immune to sunlight. He can be out in it for a little longer than most vampires, but it will eventually kill him.
- Deadpan Snarker: He's oddly amused at the nickname Fet gave to Ozryel.
- Death Seeker: Quinlan knows that by killing his father, he'll die, too, but he doesn't care.
- Dhampyr: He's the half-man, half-vampire spawn of the Master.
- Genius Bruiser: Is well-versed in ancient knowledge and effortlessly kills many, many vampires and humans.
- Even Bad Men Love Their Mamas: He's not necessarily a bad guy, although he has boasted about killing more humans than he has vampires. And he hates his father for killing his mother and making him into what he is.
- Expy: Of Blade. He's a dhampyr devoted to hunting other vampires with silver weapons, and shares a similar backstory. He also has a few similarities to Jared Nomak, which del Toro had previously worked on.
- Horrifying Hero: While he is part vampire and has a hideous appearance, he's still essentially a good guy. This doesn't stop him from occasionally taking the time to make a point about how dangerous of an enemy he could be to the heroes by draining Stoneheart mooks in front of them.
- Hunter of His Own Kind: Comes with being the Ancients' chief headhunter, and someone incredibly pissed at the Master for ruining his "life".
- I Hate You, Vampire Dad: The Master killed his mother, and later the family that the Ancients gave him. It's completely understandable why he'd hold such a grudge against him. It's also suggested that he hates him for having to live as the abomination he sees himself as.
- Really 700 Years Old: He was born sometime after Caligula's reign and has killed countless humans and strigoi.
One of the Ancients, the seven original vampires, the Master now inhabits the body of Jusef Sardu, a 19th century Polish nobleman afflicted with gigantism. While Sardu was a gentle giant in life, and greatly infirmed by his condition, the Master has imbued his form with unnatural power and ferocity. Breaking the territorial truce between himself and the other Ancients, the Master sets into motion a series of events to remake the world in his own dark image.
- Abusive Parents:
- He murdered his son, Quinlan's family, and has been trying to either turn or kill him for a long time.
- Also serves as this to Zack, who he spoils rotten, but in truth, is only trying to corrupt and groom him into his new host. He drives Zack to commit acts of evil, like shooting a snow leopard, and withholds the truth about Eph's survival from him for two years. By the time he tells him the truth, Zack no longer cares and considers him dead.
- Arch-Enemy: To Abraham Setrakian, who has dedicated his life to extinguishing his bloodline.
- Arch Nemesis Dad: To Quinlan, his Dhampyr son.
- Ax-Crazy: The Master revels in death and suffering, whether or not he's the direct cause of it. He also thoroughly enjoys murder for its own sake. Like when he smashed a woman's head to bits.
- Big Bad: The main antagonist of the trilogy, even the Ancients reluctantly agree to side with Setrakian and co to take him down.
- Body Horror: Even more than the other vampires, since his host was suffering from gigantism. Made even worse when he's burned by the sun and his skin is severely charred and constantly flakes off.
- The Corrupter: Probably had a hand in Palmer's corruption, and in the third book, he's grooming Zack to become his next host, goading him into shooting a snow leopard and slowly turning him against his father.
- Dark Is Evil: Wears a black cloak and is an ancient vampire lord that wants dominion over humanity.
- Deadpan Snarker: The Night Eternal shows that he has a very sarcastic sense of humor, particularly when Eph promises to send a copy of the Lumen instead of the original text.
- Demonic Possession: How he travels from body to body. The Fall reveals that he has to transfer a large quantity of worms to his host-to-be, hijacking their entire body and personality in the process.
- Evil Is Bigger: While he's in the body of Jusef Sardu, he's well over 7 feet tall, towering over his foes.
- Evil Sounds Deep: Is described as having a deep, guttural voice, "lubricated by blood."
- Fallen Angel: Ozryel, the archangel of death, was dismembered for killing one of his fellow archangels and his remains scattered across the world. Worms emerged from the blood of each remnant his being the throat and found human hosts, who evolved into the first Ancients.
- Fantastic Racism: Loathes humans and sees them as vermin to be either turned or subjugated and farmed for their blood.
- Faux Affably Evil: While he is persuasive and cunning, he maintains civility only as a means to an end.
- For the Evulz: According to the Ancients, this is why he does anything he does, and by all evidence, they're right. He could have dominated the planet with them, but the pain he would cause would not be personal enough to him.
- Humanoid Abomination: While most of the vampires are certainly grotesque, the Master best fits the bill for this, even bordering on Eldritch Abomination given his capacity for Demonic Possession. He is described as a "hive of undead souls" and can mask his voice using the voices of the strigoi he turned.
- I Am the Noun: I am the occultation and the eclipse.
- I Lied: Seems to enjoy pulling this one on people, with Eldritch Palmer being a good example. He even notes that if Ephraim had betrayed the humans, he would not have honored his end of the deal with him.
- Kick the Dog: Pretty often. The Master is drawn to suffering and death, so it only stands to reason that he would have some exceptionally cruel moments.
- He broke Setrakian's fingers at Treblinka, leaving him to the mercy of Eichhorst to dispose of him.
- Taunting Eph about how he "has" Kelly, and will soon take Zack. He continues this trend in later books, using Kelly's voice to speak to him, and at one point using Zack's to let him know what Zack really thinks of him.
- When he catches up with Quinlan, he murders the family that the Ancients gave to him.
- Lack of Empathy: A defining characteristic of his that screws him over quite often. He chose to force Palmer to wait to be turned, and refused to let Eph see Zack before their bargain could be fulfilled.
- People Farms: His plan was never to turn every human. Instead, it was to set up concentration camps where they would be herded in and forced to breed so that he and his fellow strigoi could have more generations of humans to feed on.
- Puny Humans: Clearly, he's not fond of the human race. A good portion of his dialogue involves him calling them "pigs" or "animals".
- Smug Snake: He is notoriously arrogant and revels in deception.
- Stupid Evil: There are multiple times where it would have benefitted him to be less smug. His forcing Palmer to wait in line to be turned resulted in him being backstabbed and his funding for the Lumen cut off, and refusing to allow Eph a chance to see Zack to ensure that he'll live up to his end of the bargain might have prompted Eph's hesitance in giving him the book.
- Voice of the Legion: Sort of. He has a "true" voice that can paralyze anyone within his vicinity if he uses it, but using it will alert the other Ancients of his presence, so he cloaks it using the voices of the vampires he turned.
- The Worm That Walks: If his possession of Bolivar is anything to go by, his bloodstream is composed entirely of worms. Then, of course, he's frequently described as the embodiment of the vampires he's turned.
A handsome and charismatic shock rocker.
- The Brute: Acts primarily as muscle to the Master.
- Expy: His appearance and shock rocker mannerisms, coupled with his popularity and use of a stage name are clearly based on Marilyn Manson.
The former Nazi commandant of the Treblinka extermination camp.
- The Dragon: The Master's right-hand man. He sets up appointments for him, and is the brains behind his operation.
- Faux Affably Evil: He's quite the gentleman for an undead Nazi. He critiques different types of blood the way one would wine.
- Off with His Head!: Setrakian chops his head off.
- Karmic Death: He's killed by the very person who endured his torments at Treblinka.
- Politically Incorrect Villain: Is a former Nazi camp commandant, and makes a pretty nasty anti-Semitic comment to Setrakian near the end.
- Those Wacky Nazis: Was a the camp commandant at Treblinka in life, and still holds onto Nazi ideologies in undeath, to an extent.
The first vampires to come into existence, divided into New and Old World Ancients.
- Big Good: They claim to be as such, in that they prevent the Master from claiming the world as his own, but they plan to do the exact same thing, with the only difference being that they're letting humanity destroy themselves first.
- Blue-and-Orange Morality: They claim to have helped keep civilization from falling apart (which is true, to an extent), and view turning humans as a reward for nobility.
- Dark Is Not Evil: "Not evil" may still be a stretch, because they still planned on world domination, but they want to eradicate the Master and are nowhere near as terrible as him. They also gave Setrakian the clues he needed to destroy him before dying.
- Death Equals Redemption: Once they along with the Master have all had their origin sites destroyed, they return to their original form, the archangel Ozryel, and ascend to Heaven.
- Demonic Possession: Presumably, they find hosts the same way the Master does.
- Even Evil Has Standards: Despite being vampires, they do not wish for the Master to Take Over the World (although they hope to claim it themselves), and his sheer sadism disgusts them.
- Fallen Angel: They share the same backstory as the Master. Ozryel, the archangel of death, was dismembered for killing one of his fellow archangels and his remains scattered across the world. Worms emerged from the blood of each remnant and found human hosts, who evolved into the first Ancients.
- Fantastic Racism: Not as extreme as the Master, but they see humans as little more than food to be eaten and their husks disposed of.
- Killed Off for Real: The Master destroys their origin sites one by one, annihilating them in the process.
- Noodle Incident: Whatever caused the schism between the New and Old World Ancients.
- Pet the Dog: They aided Quinlan in his vengeance against the Master, and even gave him a family to live with. Sadly, the Master took them away from him.
- Pragmatic Villainy: Knowing that if the Master succeeded in his schemes, he would claim the world for himself without sharing his power, they attempt to subvert him, going so far as to ally themselves with their sworn enemy, Abraham Setrakian. Of course, they seek world domination, albeit by letting mankind drive the planet into ruin without vampiric intervention.
Augustin "Gus" Elizalde
A Mexican gang member fresh out of juvenile hall, Gus is attacked by a newly turned vampire on the streets of Times Square, and is arrested by the police after throwing the creature under a truck. Learning the truth about vampires from a temporarily incarcerated Setrakian, Gus escapes confinement and finds himself to be a natural vampire slayer on the streets of his tenement neighborhood.
- Badass Normal: For a street punk, he does a pretty good job surviving the vampire plague.
- Cain and Abel: His relationship with his brother, Crispin, is not a good one, but this trope is played more straightforward when Crispin is turned into a vampire and Gus is forced to kill him.
- Defiant to the End: His final words to the Stoneheart mooks aiming at him are:Light me up, motherfuckers!
- Even Bad Men Lovetheir Mamas: He never stops caring for his mother. Not even when she becomes a vampire.
- Flat-Earth Atheist: Refuses to believe Eph's claims of seeing angels, and thinks the origin story of the strigoi is horseshit. Never mind that he's had to face them.
- Hot-Blooded: Gus is an angry, aggressive gangbanger, although he's more subdued in the company of friends.
- Jerkass Has a Point: While he's not exactly the nicest guy around, he's right that Eph, in his depression, is holding the team back. It helps that Eph was willing to sell them out along with the whole human race just to see his son again.
- Jerk with a Heart of Gold: For all his irrationality and anger, he genuinely loves his friends and his mother, to the point where he keeps her and feeds her his own blood after she'd been turned.
- Unwitting Pawn: In the first book, he unwittingly helps the Master get across the bridge. In the sequel, The Ancients manipulate him into becoming their agent.
One of the richest men in the world, Eldritch Palmer craves the one thing that all his money cannot buy: immortality. The elderly tycoon's fear of death leads him to make a pact with the Master, trading his vast fortune, political influence, and the fate of the human race in exchange for an undead place at the vampire king's side.
- Evil Cripple: All his life, he's suffered from an unnamed terminal illness, and helps the Master in his ambitions.
- Evil Old Folks: An elderly man who serves the Master.
- Faux Affably Evil: Especially in his conversation with Eph.
- Half the Man He Used to Be: He is ripped in two at the waist and chucked against a wall.
- Off with His Head!: The Master rips his head off just when it looks like he's going to turn him.
- Rewarded as a Traitor Deserves: As someone who sold out the human race just so he could become a bloodsucking monster, he earned his gruesome death.
Dr. Everett Barnes
As the Director of the Centers for Disease Control, Barnes is Eph and Nora's direct superior. Skilled in the politics and media aspects of the medical industry, he is a shrewd bureaucrat who carefully maintains a quaint, "country doctor" image.
- Beard of Evil: Sports a very satanic goatee in The Night Eternal.
- Dirty Coward: Hopped on board with Stoneheart and the Master because he saw any attempts to fight back as pointless.
- Faux Affably Evil: He best demonstrates this when he politely tries to get Nora to perform certain services for him in exchange for a degree of freedom.
- Humans Are the Real Monsters: Discussed by both Nora and Eph. Nora calls him "worse than a vampire", due to vampires having a need for blood, whereas he just enjoys sexual extortion; Eph calls him a vampire despite having not been turned.
- It's All About Me: His own life is his first priority, the well-being of others be damned.
- Karmic Death: Shot by Nora who he tried to extort and left to the mercy of a horde of hungry vampires.
- Smug Snake: As the Master himself an example of this he's nowhere near as smart as he thinks he is.
A member of the CDC and assistant to Dr. Goodweather.
- The Mole: He's working for Stoneheart and pretending to be friends with Nora and Eph.
- We Hardly Knew Ye: Jim is barely given any characterization, even after he dies.
- Jerk with a Heart of Gold: He's an asshole to Eph, but he does genuinely care about Zack and Kelly.