Four Horsemen of the Apocalypse

Info
General traits of The Four Horsemen of the Apocalypse in the Supernatural Verse The Four Horsemen of the Apolcalypse and the Antichrist as described in the book of Revelation are part of the apocalyptic destruction of Earth. They are generally described as War, Death, Famine and Pestilence (also described as Conquest or the Anti-Christ himself) - each riding a different coloured horse.
 * The Four Horsemen seem to be set strongly on their assigned missions.
 * They are extremely powerful.
 * Their true origins currently are unknown, as is the method of destroying them.
 * It has yet to be confirmed whether, The Horsemen are High-Ranking Angelic figures or if they're Demonic figures with extreme amounts of authority.
 * Horsemen are immune to Sam's powers.

Known Horsemen
"I have three siblings and we're so much fun together."

''- War, from "Good God, Y'all"

Heralds of the Apocalypse and either very high level demons or something more powerful, the Horsemen had up until this point been relatively idle; existing in a sort of multiple existence all over the world where their specific elements preside. War describes his life before the breaking of the Seals as being all over the place, more specifically existing where every major war in human history has taken place. Now that Lucifer is free, they have begun to up the stakes and spread their powers across the Earth to turn it into Hell on Earth.

In Death Takes a Holiday Alastair remarks the Horsemen are well aware of Lilith's plans and "are jonesing for the Apocalypse".

Unlike demons or higher-tier demons like the Seven Sins, the Horsemen are virtually indestructible. The only way to destroy them would be to annihilate all war, famine, pestilence and death in the world. Though in The Devil You Know it is revealed that separation from their rings leaves them in a withered near catatonic state.

The Horsemen have a very slanted view of humanity and see themselves as just bringing out in humanity what is already there. Both War and Famine have said humans "only need a little push" in order to do horrible things, and both have surprisingly shown a level of disgust/contempt toward how easily corruptible humans are and what they can do.

It is unknown if their human forms are constructions, illusions, or actual human vessels; Anna hinted that they may be using vessels when speaking to Castiel saying "The horsemen can go back to their day jobs" once the Apocalypse has stopped.

Each Horsemen also possesses a glass ring that allows them to channel and focus their power, and while it doesn't kill them, separating them from their rings is the only known way to drive them off. So far the brothers have acquired the rings of War and Famine. In Hammer of the Gods Gabriel revealed the rings are actually the keys to Lucifer's Prison and if the brothers can collect all of them and trick Lucifer back to the cage, they can be used to open and reseal the cage.

It also hinted that Lucifer may not have total control of the Horsemen as it is revealed in the upcoming episode The Devil You Know that Dean and Sam are instructed to find Death and Pestilence's handlers in order to acquire the rings. Lucifer said in Abandon All Hope... that the Horseman (Death in this case) are very demanding and it requires certain rituals and agreements to keep them happy and compliant. Their handlers are revealed in The Devil You Know to be more like personal attendants seeing to each Horseman's personal needs and overseeing some of their interests. Brady for example has been overseeing Pestilence's Croatoan trials while the Horseman has been setting the stage for the virus's release.

War
Appearing in "Good God, Y'all", War arrived in Rufus' town in the guise of a well known resident who he had previously killed a few nights ago. In the Bible, he is said to ride a red horse but these days he has "got with the times" and travels in a red sports car. Once in town he destroyed the only exit from the town and then got to work on the people of the town by using his ring to generate hallucinations making the people believe that others around them had been possessed by demons. War hates acting directly because in his opinion the best way to cause chaos is to cause panic and let humans take care of the rest. Realizing that they could not kill War because the only way to do that would be to destroy all war in the world, the Winchesters instead cut off his ring finger, breaking the spell he had cast over the town and forcing him to depart. In The Devil You Know Brady reveales the Winchesters have reduced him and Famine to near catatonic states.

Famine
Famine appears in My Bloody Valentine as an old sickly man. Improvements in farming and agriculture have severely weakened Famine, resulting in his sickly and weakened state. Because of his weakened state, Famine can barely infect anyone by himself, forcing Lucifer to send lower level demons to the Horseman to care for him until his powers are fully regenerated. Despite his weakened state, he is still strong enough to resist an assault from a Demon blood juiced Sam and explains all the Horsemen are immune to Sam's powers. Like his brother War, he too possesses a ring that allows him to focus and direct his powers.

Pestilence
Pestilence first appears at the end of Hammer of the Gods when he bought flu medicine from a small drug store, and spread some disgusting mucus over everything. He drives a sickly green/white car with a license plate that spells "sick and tired". He is accompanied by a swarm of flies and has the appearance of a man suffering a heavy cold though this appeared to be a ruse for after leaving the drug store he straightens up and laughs while throwing the medicine away.

Death
Death didn't make a physical appearance in Abandon All Hope..., but his presence was released from its prison in this episode. Lucifer released Death with his ritual. Although not seen on-screen, Death showed up and caused the dead to rise from the grave in Dead Men Don't Wear Plaid. We will meet his physical form in Two Minutes to Midnight, where Dean will strike a dangerous deal with him in exchange for his ring.

Family

 * Each other (kindred)

Season 5

 * Good God, Y'all
 * Abandon All Hope...
 * My Bloody Valentine
 * Dead Men Don't Wear Plaid
 * The Devil You Know
 * Two Minutes to Midnight