Human

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.

Powers and Abilities
The primary abilities of every human being include adaptability and versatility. For the most part, humans are outmatched by supernatural beings and are most often defeated whenever confronted by a superior creature. However, some humans have been known to utilize tools and weapons and have managed to succeed in a supernatural combat. Therefore, as a means of survival, most humans must rely on intelligence, research and teamwork in order to prevail.

Due to the fact that humans are commonly noted for their tendency to fear the unknown, many of the humans who are aware of the supernatural have built societies, such as the Town Council, that are dedicated to hunting and killing all supernatural beings, especially vampires. Generally, these hunters use advanced knowledge of folklore to hunt, identify and murder any and all threats to humanity. They are able to modify conventional human weaponry such as guns and knives to repel and/or kill supernatural beings that are often more powerful than they are.

Humans who are born with magical powers are known as "witches". While most witches are known to channel their power from the forces of nature, some witches, such as the New Orleans Coven, have been known draw their power from other sources. Witches who have great command over magic have proven to match, or in the case of Qetsiyah, overpower other supernatural beings.

Weaknesses

 * Mortality: Humans have weaknesses, (e.g. age, decapitation, disease, heart-failure, suffocation, etc).
 * Blood Loss: If a human is severely wounded and bleeds out they can die.
 * Broken Neck: Breaking a human's neck will result in instant death.
 * Decapitation: Decapitation will result in instant death for a human.
 * Fire: Fire can kill a human. It can also hurt them.
 * Heart Extraction: Ripping a human's heart out will result in instant death.
 * Magic: Humans are susceptible to the powers of witchcraft, which includes both spells and certain magically empowered objects.

The Vampire Diaries

 * Elena Gilbert
 * Matt Donovan
 * Alaric Saltzman
 * Elizabeth Forbes †
 * Carol Lockwood †
 * Meredith Fell
 * Jamie
 * April Young
 * Liam Davis
 * Sarah Salvatore

The Originals

 * Camille O'Connell
 * Will Kinney
 * Kieran O'Connell †
 * Tim †
 * Sean O'Connell †

Vampires
Only a handful of humans are aware of the existence of literal vampires. Among the greater masses of the 21st Century, vampires are regarded as superstition, fiction, and myth. Humans can be turned into a vampire, with vampire blood and then death, although it needs to happen within 24 hours. Some humans can be completely unaware of what's happening to them during their transition into vampirism, and will feel confused and very hungry, much like Caroline Forbes when she first turned.

It appears that humans are more aware of vampires in New Orleans, than anywhere else. Indeed, among the various factions who live together in this city, even the human is of considerable importance, and often act as a mediator between the vampires, wolves and witches, as shown several times by the priest Kieran O'Connelland, later, by his niece Camille O'Connell. Humans and Vampires here co-exist without problems due to the 'treaty' each faction representative must sign with blood. Vampires are so exposed here, their existence is revealed on New Orleans tours.

Werewolves
Not very many humans are completely aware of werewolves, mainly due to their near extinction, making them an endangered species. Humans can also give birth to werewolves. Werewolves are technically still human until they trigger the curse (Tyler Lockwood being compelled by Damon Salvatore and Eve not being able to heal at a rapid state, being proof). They can pretty much grow up living a human life unaware of their heritage, such as Hayley Marshall and Richard Lockwood.

Witches
Some humans might not be completely aware of witches, but they are most likely aware in New Orleans, and sometimes used in human witchcraft practices or sub-culture classes. Back in the Salem witch trials, humans were held responsible for the burning of the witches, especially Emily Bennett. Despite the horrible history between the two species, it appears that witches can generally get along with humans, possibly mainly because they are bound by nature. Humans can give birth to witches, and can also lose their powers, becoming human.

Witches (much like werewolves) can also be completely unaware of their heritage and will most likely confuse them when their abilities start to break out, much like Bonnie Bennett.

Doppelgängers
Only a handful of humans are aware of their existence. Humans can give birth to a doppelgänger and a human can become one, if they took the immortality spell, and distributing the balance of nature. Despite still being human, a doppelgänger is still considered supernatural.

Ghosts and Mediums
Only mediums and witches can communicate a ghost. The only way a human can make contact with a ghost is if the veil to the other side breaks down, meaning ghost domination. Mediums are still human, but with special abilities. They are humans who died (non-supernaturally) and have been resurrected by a witch, possibly leaving a "door open" for contact with ghosts.

But since the other side is destroyed it is unknown if mediums can still communicate with ghosts.

Supernatural Hunters
Humans are little aware of supernatural hunters and what they stand for. A human can become one, if they can notice the hunter's mark on another hunter, then they become awakened after the other hunter dies. With the enhanced strength and agility, supernatural hunters will have strong urges to kill vampires, even when they don't want to, or have never had a problem with vampires in the first place.

Trivia

 * Many characters refer to being "human" in the same context as being "mortal", however, the terms are not synonymous as many supernatural creatures are considered mortal (vulnerable to death), but humans are another species altogether. This error can be dismissed, however, as many characters do it informally.
 * Humans can become mediums if faced with a near-death experience.
 * Humans can be turned into vampires.
 * Humans can give birth to doppelgängers, werewolves, or witches.
 * The human race is the oldest species known to man, alongside witches and possibly werewolves.
 * The human race is the most fragile species in the series as they can die from many weaknesses such as age, disease, and many other natural causes.