Humans are a race of mortal, sentient beings who are members of the species "Homo Sapiens". Humans serve both as a food source as well as a means of pro-creation for vampires, who reproduce by performing a ritual that will transform a human being into an undead immortal. Humans make up for the majority of the earth's population, and are commonly noted for their desire to influence and understand the environment by seeking to explain and manipulate phenomena through mythology, philosophy, religion, and science.
A witch is a person who is born with the power to affect change by magical means (Witchcraft). While many witches are the self-proclaimed "Keepers of the Balance," other witches have been known to work against the Balance and use their power for personal gain.
Doppelgängers, also known as Shadow-Selves or Mortal Shadow Selves, are a supernatural occurrence that were created by Nature as a result of Silas and Amara becoming true immortals after consuming Qetsiyah's immortality elixir. The purpose of this supernatural species is to maintain the natural balance by dying in place of their immortal progenitors. For this reason, doppelgängers have existed for at least 1,000 years during which time they have been born and died in the place of Silas and Amara, who, as true immortals, were invulnerable to any conventional weapon. There are two known doppelgänger lines which stem from Silas and Amara, respectively. Known doppelgängers of Silas are Stefan Salvatore and Tom Avery, and known doppelgängers of Amara areTatia, Katherine Pierce and Elena Gilbert. As of Season Seven, Stefan Salvatore and Elena Gilbert are the last remaining doppelgängers.
Werewolves (also called Lycanthropes, Loup Garou, Beasts, or even just Wolves for short) are a near-extinct supernatural shapeshifting species of individuals who unwillingly transform into large, fearsome, and extremely hostile wolves on the night of the full moon. Even in their human form, werewolves possess superhuman physical prowess, though not to the same level as a vampire, and their abilities are not as powerful compared to those they possess on the full moon while transformed. These creatures are the most dangerous enemies of vampires due to their venomous bite, which is lethal to them. Werewolves are also hardwired to kill vampires on sight in their wolf form, though they still hunt human prey whenever there are no vampires to kill.
A Passenger is the spirit of witch (traditionally a Traveler) who lays dormant inside another person's body until activated by a magical code word or incantation. According to Katherine, they lay dormant like parasites inside the body of their host until activated. Passenger spells are primarily used by the Travelers as a way to possess other bodies without facing the consequences of their Travelers' cursewhile practicing magic as a group in their own bodies.
Siphoners, or Siphons, are a subsection of witches born without the ability to generate magic, but a rare power allowing them to siphon off from other magical sources. They are considered abominations by many witch communities despite being born with their abilities and may face harsh treatments towards their covens when discovered.
Supernatural Hunters are humans spelled to gain supernatural abilities to hunt and kill vampires and werewolves.
KNOWN SUPERNATURAL HUNTERS:
A medium was a person with the power to communicate with thespirits on the Other Side. There were once two ways that a person could gain mediumship. The first was for a human to die and then beresurrected, either by magical or medical means, giving them a connection to the dead. Examples of mediums who gained their abilities by this process are Jeremy Gilbert, who was resurrected by magic, or Matt Donovan, who was brought back to life with CPR. The other way was to be the Anchor to the Other Side, such as Amara orBonnie Bennett, as the supernatural role allowed them to exist both on the Other Side and in the living world at the same time. Since the collapse of the Other Side, mediums can no longer contact the spirits of the dead, as the spirits have now moved on to otherafterlife dimensions that are (as far as anyone knows) currently inaccessible to those in the living world
Mermaids are born with the powers. They do live in the sea. Humans can turn into mermaids when they entered the Moon pool during the full moon