Aliens

Aliens are of yet unconfirmed species that may or may not exist outside of Earth.

Overview
Aliens have not appeared officially and are mostly regarded as fiction. Those who believed in aliens are seen as delusion or mentally unstable. Aliens are generally believed to be small green men with big black eyes.

The Trickster conjured aliens and used them to abduct a college student named Curtis. Curtis was visibly shaken by the experience, and recalled the aliens prodding him and forcing him to slow dance.

A leprechaun known as Wayne Whittaker posed as a UFO-specialist after being summoned to Earth. His kin, the fairies, begin kidnapping all first-born sons in an incident that was believed to be the result of ailen abductions. The abductions also led to a gathering of UFO watchers, one of them being Sparrow Jennings.

One of the future prophets gathered by Crowley assumed Crowley was an alien at the meeting. Another prophet asked if they were on Crowley's spaceship.

A homeless man who witnessed JP's abduction by Hansel claimed the abduction was done by aliens.

When people start disappearing in Gunnison, Colorado, Dean Winchesters wonders if aliens are responsible. The true culprit is a Bisaan.

Appearances

 * Season 2
 * Tall Tales (mentioned only)
 * Season 6
 * Clap Your Hands If You Believe (mentioned only)
 * Season 8
 * A Little Slice of Kevin (mentioned only)
 * Season 10
 * About a Boy (mentioned only)
 * Season 11
 * The Chitters (mentioned only)

Trivia

 * According to Eric Kripke, there are no such thing as aliens in the Supernatural universe.