Immortals
Immortals are superhumans who carry a virus granting them seemingly eternal life (unless they die by violence). Loosely speaking this can collectively refer to Vampires and Lycans, but strictly speaking a true "Immortal" has the immortality virus with none of the animal genetic fusions.
Description
Immortals would seem to not to be very different from normal humans, Alexander Corvinus having lived amongst humans for most of his sixteen hundred year life hiring them as soldiers and servants as seen with his Cleaners, although it remains unknown how many of them were aware of his immortality.
Background
Immortality was granted by the active Corvinus Strain, created in the early 5th Century as Alexander was infected with a plague virus which due to something unique about him mutated. Turning Alexander into the first Immortal, this same virus was inherited. The Immortal viruses of his twin sons William and Marcus were mutated after they were bitten by a wolf and bat respectively turning them into the first Werewolf and Vampire.
Powers and Abilities
Not much is known about an Immortal's abilities. It is unknown if Immortals could bite and infect humans with a virus like Vampires and Lycans. It is also unknown if an immortal has healing powers. When Alexander Corvinus was stabbed through the chest, he indicated he was dying and ended up blowing himself up. It is unknown if he could have healed the wound and simply chose not to and decided to die or was unable to heal the wound.