The Colt

The Colt is a revolver made by the hunter Samuel Colt. John Winchester had been searching for it for many years. According to legend, anything shot by this gun, using one of its thirteen original bullets, will die, including supernatural creatures normally immune to any and all weapons. On several occasions, it was in the possession of Sam and Dean Winchester, who used it to kill demons, vampires, a phoenix (through time travel) and the demon Azazel.

Appearance
The gun used in the series is actually a replica Colt ball and cap gun modified to fire metallic cartridges. On the barrel of the gun is inscribed the Latin phrase "non timebo mala", meaning "I will fear no evil".

On the handle is a carving of a pentagram, with much of the finish removed to give it an aged appearance. It originally came with 13 bullets - eight were used before the Winchesters obtained it, and they used the other five. It then no longer worked. However, the demon Ruby and Bobby Singer, managed to make more bullets for it.

Overview
The legend of The Colt, as told by John Winchester, is as follows:

"Back in 1835, when Halley's Comet was overhead, the same night those men died at the Alamo, they say Samuel Colt made a gun...a special gun. He made it for a hunter -- a man like us, only on horseback. The story goes he made 13 bullets. This hunter used the gun a half dozen times before he disappeared, the gun along with him. Somehow, Daniel got his hands on it. They say -- they say this gun can kill anything."

- John Winchester

When John Winchester became aware of the power that the weapon had, he began to search for it so that he could use it to kill the demon that killed his wife - Azazel. He and his sons finally obtained it after a vampire killed the owner, Daniel Elkins, and the Winchesters attacked the vampire's nest to get it back. However, John gives it to Azazel in return for Dean's life being spared after an almost-fatal car crash, and at the end of the second season, Azazel uses it as a key to open a gateway to Hell that Samuel Colt had sealed. Dean uses the last original bullet to kill him.

Towards the end of the third season, the gun was stolen from them by Bela Talbot in order for her to get out of her contract with a Crossroad Demon. She told the Winchesters that she gave it to Lilith, but in fact she instead gave it to a demon named Crowley, who hid it. After Castiel and the Winchesters track down Crowley he returns it so that they can kill Lucifer. The boys find Lucifer and Dean shoots him straight through the head but Lucifer, although unconscious for a few moments, awakens and is unharmed, although it was painful, and he mentions he is one of five things in all of creation that the Colt cannot kill. It is seen once more when the Winchesters travel to 1861. Dean drops the Colt just before being transported back to the present day, where it is retrieved by the saloon owner Elkins, a possible ancestor of Daniel Elkins, who possessed the weapon at the beginning of the series.

Usage
The Colt's original thirteen bullets could kill almost anything; there were only five things in all of creation (including Lucifer) that couldn't be killed by the revolver.

After using all the bullets, Ruby somehow helped Bobby make other bullets that can kill supernatural monsters. The Colt has a second function: the barrel of it acted as a key to unlock a Devil's Gate, as seen in the episode All Hell Breaks Loose - Part 2.

The following denotes the known uses of the Colt with the original "Samuel Colt" bullets shown in the color grey:

Trivia

 * The props department of the show has a rubber version to be used in fight scenes for pistol whipping.
 * The design of the Colt appears to be a stylized Colt Paterson black powder revolver, patented by Samuel Colt in 1836.
 * Despite being in the possession of Hell during the ushering of the Apocalypse, the Colt (along with Death's Scythe) was never used by demons offensively against angels.
 * The Colt has appeared at least once in every season, except Season Seven, Season Eight and Season Nine.
 * As Eric Kripke mentioned he was inspired by Hellblazer, it is possible that the Colt was based on the Ace of Winchesters, a magical rifle from the Old West that John Constantine of the Hellblazer series uses to instantly kill demons. It is interesting to note that the name of the rifle also shares the surname of Sam and Dean.
 * The five created beings that cannot be killed by the Colt include Lucifer, so it presumed that beings as strong or stronger than him are also immune. This presumably includes the archangels, the horsemen, the Leviathans/Eve and God.