The range of Demonic eyes.
What do yellow, red, white and black all have in common?

All fans of the television series Supernatural know the answer to this question. It’s the few different eye colours associated with demons in the show. In religion and mythology, occultism and folklore, a demon is a supernatural being that is generally described as a malevolent spirit.

First seen in the season four episode, Phantom Traveler, demons continue to play a major role throughout the entire five seasons and probably will until end of the new season. The most essential aspects that relate to Dean and Sam Winchester began in 1973 when a deal was made and Sam was visited ten years later, fed demon blood, his mother killed and his father driven to become a hunter and train his sons.

Within Supernatural, the history and background on demons is shrouded in mystery, however, the third season episode Malleus Maleficarum reveals that some demons were once human, their souls having been corrupted after spending hundreds of years in Hell. After their corruption, their corporeal form becomes black smoke that generates electromagnetic interference. Subsequent seasons expands on their history further by tying it to Christian mythology, explaining that the first demon was Lilith, whom the fallen angel Lucifer corrupted himself as revenge against his father, God. However, Lucifer was soon locked away in a cage in Hell by his older brother and Archangel, Michael.

But there are other demons in the show that play important roles too. Meg, a black-eyed demon, who worked for Azazel, tracking down Dean and Sam and who taunted them at every corner, even going so far as to possess Sam for a short time.

Ruby, a black-eyed demon, takes control of Sam and helps him use his powers and provides demon blood in order to improve them after Dean’s death. In the end, Ruby plays a critical role in freeing Lucifer.

Alastair, a white-eyed demon, is revealed to be a torturer in Hell, having had both John and Dean on his rack. Alastair is also extremely powerful among demons, being able to resist Ruby’s knife, resistant to an angel’s power of exorcism and being able to send angels back to Heaven.

Crowley, the King of the Crossroads, is the one who gives Dean and Sam the colt back, wanting them to kill Lucifer, saying that if he wins the demons are next on the fallen angel’s hit list. But with the failure of its inability to kill the Devil, Crowley becomes a target for demon retribution and he helps in the location of Death, borrowing Bobby’s soul in order to find his location, a story line which is still open.

But of course there are many other demons throughout the series including - Samhain, the demon of Halloween, several crossroad demons who have red eyes and make deals, the seven deadly sins which were released when the Devil’s Gate was opened and not to mention the many other demons used throughout the show as odd episode antagonists or bodyguards for higher demons.

Personally, I have always loved the introduction of demons and even now I still find them interesting and an exciting addition to show, even after all these seasons and episodes. Some people might think it’s getting old after all this time but I strongly disagree. Evil is never boring.
Azazel - The yellow-eyed demon.