Pestilence

Pestilence is an extremely powerful entity, embodying illness and irritation amongst humans. Pestilence, also known as the Green Horseman, is affiliated with War, Famine and Death. Pestilence is one of the Four Horsemen of the Apocalypse. Due to the times and technology, Pestilence travels in a green Hornet Wagon which represents his green steed. He manifests physically on Earth by mimicking human form, specifically assuming the form of a tall, sickly, old man.

Physical Appearance
Previously being only a key element of Earth, Pestilence had no form nor depth to him. However, upon taking him form with his ring, he appeared as a tall, sickly old man.

Hammer of the Gods
At a small drug store, a large fly lands on the clerk's desk as the clerk reads about a viral epidemic that has been going around the area, but before he can swat it, Pestilence enters the store, hacking and coughing up gobs of a disgusting mucus and spreading it all over everything in his reach as he looks for some flu medicine. When he takes it to the counter, he sneezes more of his mucus into the clerk's face, likely infecting him with the latest virus he has been spreading in the area. When Pestilence leaves the store, he gets in his sickly green beaten-up Mustang, tosses the medicine aside and smiles to himself as a swarm of flies fill his car all around him, revealing that his "illness" is merely a ruse so he can spread his diseases and infect as many people as he possibly can.

Like his fellow horsemen, he has been busy spreading his influence across the land, and according to the paper the clerk is reading, he has already spread several contagious diseases in the area. When in the disguise of an ill traveler, he tells the clerk he still has "a lot of driving to do", implying he has many more tricks up his sleeve.

The Devil You Know
Since the previous episode, the brothers have been chasing after him, always one step behind him. He has been causing mass outbreaks of the Swine Flu, something the brothers find strange because Pestilence could do much worse, such as the Croatoan Virus for example. It is revealed over the course of the episode that the Swine Flu outbreak is part of a bigger plan Pestilence is working that will eventually involve the Croatoan Virus. Having infiltrated a major drug company, his servant Brady and a few other demons have begun testing the virus on unsuspecting humans in the labs at night, with the eventual plan being to disperse the virus among regular Swine Flu vaccines to cause a mass outbreak.

Though not seen in the episode, Brady communicates with Pestilence through the use of an identical goblet filled with blood of a human victim, similar to the method used by the Meg Masters. While we do not hear his voice, several flies appear from the goblet, and Brady explains that the trials are proceeding as expected, but that they must be careful as to not arouse suspicion. Pestilence seems pleased with the news, but informs Brady that should he fail, he can always find another demon to replace him.

Two Minutes to Midnight
In the beginning of the episode, Pestilence is revealed to be hiding in a retirement home, posing as a "Dr. Green". He is seen examining an elderly patient, infecting her with various diseases and observing the effects they have on her before she dies. When he is alerted by a demon posing as a female nurse that the Winchesters are here, he decides to infect them with various diseases, despite the demon's reminder that Lucifer has ordered them not to be harmed. He greets the Winchesters as they stagger towards his room, suffering from Pestilence's powers and has the demon nurse bring them into the room. He goes on to tell them that he prefers diseases to people, and how he can't understand why God loves something so "messy and weak". As he moves in to finish them off, Castiel arrives and Pestilence is surprised to find that the low-powered angel is now succeptible to his powers. Despite his weakened condition, Castiel manages to cut off his ring finger and kill the demon nurse. As his powers begin to wear off of the trio, he says "It doesn't matter. It's too late," before vanishing.

Sam and Dean later learn that he referred to his and Lucifer's plan to spread the Croatoan virus through shipments of swine flu vaccine.

Family

 * Famine (Brother)
 * Death (Brother)
 * War (Brother)

Powers and Abilities

 * Ailments Affinity- Pestilence can create and manipulate diseases, plagues, infestations, molds and other ailments.
 * Indestructiblity – Pestilence himself, as a Horseman, cannot be physically destroyed. Pestilence, like the other two riders, requires a colored ring that respectively channels his essential core abilities. Although in the case of Death, he doesn't appear to be weakened when he removes his ring.
 * Immortality – Pestilence is not subjected to death and disease.
 * Teleportation – Pestilence can go anywhere he chooses in the universe.
 * Telekinesis - Using this Pestilence caused his appearnce to blured on film, as such his face and ring were masked by static.
 * Super-stamina - Pestilence requires nothing to keep him going.
 * Invisibillity - As a horseman, Pestilence is naturally invisible and can only be seen if he wants others to see him.

Season 5

 * "Hammer of the Gods"
 * "The Devil You Know" (Unseen)
 * "Two Minutes to Midnight"

Trivia

 * Pestilence's license plate reads "SIKN TRD", which translates to "sick and tired".
 * His ring is solid silver with a sickly green gem in the centre.
 * Even though Pestilence is the White Horseman of the Apocalypse, he rides a sickly green "horse", which is generally supposed to be the Pale Horse Death is meant to ride, but instead Death rides the White "horse".
 * Pestilence appears to be jealous of mankind, evidenced by his statement "So I wonder why God pours all his love into something so (screaming) messy (he pauses slightly) and weak!"