The Afflicted, also known as Vampires, are humans who have been infected with an ancient virus that grants eternal youth and life, among other supernatural characteristics, at the cost of requiring a diet of fresh human blood. The virus is spread by the drinking or transfusion of blood from a host who is already infected. The transmission is referred to as "turning" a victim. This virus seems to have originated among the central European forests (Carpathian Mountains), where F.W. Murnau contracted the virus while conducting research for his film 'Nosferatu' in the 30s, having then spread the virus to other people, including Rudolph Valentino. At the Hotel Cortez, Countess Elizabeth is the oldest and primary host, acting as a matriarch to those whom she has turned.
The afflicted seem to look exactly like regular humans, oftentimes known for being "beautiful" due to one attractive afflicted spreading the virus to another attractive person, though they can also appear average. Upon being turned, a human inflicted with the virus dies before returning to life as one of the afflicted, stripped of their mortality; a person who is already dead can also be brought back to life via the virus's effects. As a result, the afflicted have very pale skin and low body temperature, at 75.5 degrees.
They cannot age or grow old since they stop aging once turned; Ramona Royale compares this to being "frozen in amber". The virus causes biological changes in the hosts, endowing them with heightened senses and greatly increased physical abilities such as a supercharged immune system, granting them immunity from illnesses, diseases, viruses and other infections. They also possess a variety of superhuman physical abilities, including enhanced strength, speed, agility, reflexes, senses, endurance, durability and accelerated healing, as well as the power hold sway over their chosen victims' minds, enthralling them in order to feed on their blood. They are able to eat normal food as well, though it does not sustain their life or provide nutrition in the same way as blood.
They have increased sensitivity to light, especially sunlight, which momentarily weakens their supernatural qualities. They cannot appear in photographs, as still images of them appear blurry and unidentifiable, mistaken for a technological problem by the unwary. They don't die from starvation and suffocation, but can be killed via severe physical trauma or firearms, due to hemorrhages and bleeding. Their blood virus cannot heal mental illness, such as dementia or Alzheimer's, and merely halts these illnesses from progressing opposed to healing the neurons. 
Characteristics and Powers
- Blood diet: They sustain themselves on the blood of a living and healthy human. Blood from deceased or diseased people can be very dangerous to them, and is described as having a vile taste. Afflicted have human-like physiology, and their bodies continue to function normally as long as they have a steady diet of fresh human blood. They are able to eat normal food as well, though it does not sustain their life or provide nutrition in the same way as blood. Due to their acute senses, the blood of a human who has recently consumed drugs or alcohol can leave an afflicted with the aftereffects. Deprivation of blood leads the afflicted to become rachitic creatures, similar to living mummies. 
- Immortality: The afflicted never age and are immune to disease and illness. They are able to survive without blood, although they will experience a ravenous craving for it that leaves them in a bestial state of mind, during which they develop symptoms akin to a high fever. Despite their eternal lifespans, they can be killed via shotgun or laceration, from which they will bleed to death like a normal human. 
- Regeneration: The afflicted heal from any wound as long as they are fed, regenerating all non-lethal damage at an accelerated rate. Neurons and mental illness are not healed, but merely prevented from progressing. Particularly grievous injuries, such as bullet wounds, take a longer time to mend on their own compared to other wounds, but can be sped up if the injured afflicted feeds off the blood of another afflicted.
- Superhuman Abilities: The afflicted are naturally superior to humans in almost every way, possessed of otherworldly senses which allow them to easily outrun and overcome their mortal prey. They are able to see in the dark, hear a human's heartbeat, and identify specific individuals based off the scent of their blood, allowing them to track others over long distances. Ramona Royale describes Elizabeth's blood as smelling like "black licorice", while Elizabeth describe's Ramona's as smelling of "walnuts". The blood of those who abuse drugs and other substances can also be identified, as Elizabeth describes Tristan's blood as smelling of "copper".
- Concilium (Possibly): The afflicted seem to possess some limited control over others' minds, which they often use to seduce hapless men and women. When Elizabeth and Donovan go to the showing of Nosferatu, they attract the attention of a human couple merely by turning their gaze on them, causing the couple to turn their heads from watching the film to watching Elizabeth and Donovan. Elizabeth later uses this power on Donovan when he refuses to go to Will Drake's fashion show, and then on Tristan during the events of said fashion show, preventing him from stabbing an attendee. In 1977, Elizabeth prevents a producer from taking advantage of Ramona Royale by glancing at him and commanding him to leave, and he does so without question.
- Transmutation (Possibly): The afflicted may or may not have the power to instantaneously teleport to different locations at will. Elizabeth was able to appear in front of Vendela during her attempted escape from the Hotel Cortez, unemotionally slicing her throat to prevent her from getting help from the outside world, and later appeared suddenly behind Alex Lowe upon the mortal's discovery of the hotel's former pool housing the resting places of several vampiric children. It is more likely that this power is the enhanced speed possessed by the afflicted, though the manner through which scenes were filmed throughout the season of afflicted appearing seemingly out of nowhere leave this up to speculation, as the afflicted have never been directly seen moving at supersonic speed.
- Power Absorption (Possibly): The afflicted are able to obtain and use supernatural abilities from other creatures by draining and drinking their blood. Ramona refuses to take weapons offered by Liz Taylor after drinking the blood of Queenie, a powerful witch; she describes this as a feeling akin to "bears running through [her] veins". It is unknown if this effect is permanent or temporary, though she never demonstrated this on the screen.
- Nocturnal: The sun presents no real danger, only weakening their supernatural abilities. As a result, they prefer to hunt at night and sleep in the day. Elizabeth's "children" even sleep in coffins, but this may be merely an affectation. Elizabeth, by her own admission, prefers to sleep with the curtains drawn to dim the light.
Though Ryan Murphy is adamant in distinguishing the virus and those afflicted by it as creatures separate from the long standing, historic icons known as vampires, the afflicted are still quite clearly an homage to the fictional creatures.  Valentino was originally turned by the director for the film "Nosferatu", which details the story of a bat-like European vampire that feeds on blood. In this universe, actual vampires are "ugly demons", while the afflicted are beautiful.
- F.W. Murnau
- Rudolph Valentino (deceased)
- Natacha Rambova (deceased)
- Elizabeth (deceased, currently a ghost)
- Ramona Royale
- Prophet Moses (deceased)
- Donovan (deceased)
- Wren (deceased)
- Holden Lowe
- Tristan Duffy (deceased, currently a ghost)
- Alex Lowe
- Max Ellison (deceased)
Blood Brat Pack
(NOTE: Blood Brat Pack is an AHS Wiki construction inspired by the first season's Dead Breakfast Club.)
Also informally known as 'the towheads", these are Elizabeth's pale-blond adopted children consisting of one girl, Wren, and three boys, including Holden Lowe. When not sleeping in their art-Deco glass coffins, they roam freely within the halls of the hotel, often spooking the guests. The blood upon which they feed is filtered by a dialysis machine and decanted as a luxury beverage for their matron.