The 1835 Colt Paterson revolver, usually referred to as "the Colt", was made by Samuel Colt, a paranormal hunter. According to legend, anything shot by this gun, using one of its thirteen original bullets, will die, including creatures normally immune to any and all weapons. John Winchester gives it to the demon Azazel in return for Dean's life being spared after a near-fatal car crash. At the end of the second season, Azazel uses the Colt as the key to open one of the Gate of Hell that Samuel Colt had sealed. The last bullet is then used to kill Azazel, though the gun is later altered to allow the use of more bullets.
Towards the end of the third season, Lilith's right-hand demon, Crowley, acquires the gun and hides it. It is then featured in two time-travel episodes – Dean using a past version of it when he is sent back to 1973, and his future self discovering it when Dean is sent five years into the future – before Crowley returns it to the Winchesters so they can kill Lucifer. However, after Dean shoots Lucifer in the head at point-blank range, an unharmed Lucifer boasts there are five things in creation which the gun cannot kill, and he is one of them.
It is unknown what happened to the weapon after that point, as its only subsequent appearance on the show was a chronologically earlier version, seen when the Winchesters travel to 1861. Sam gets it from Samuel Colt, and Dean uses it to kill a Phoenix, as they need its ashes. Dean drops the Colt just before being transported back to the present day, where it is presumably retrieved by the saloon owner Elkins, the ancestor of Daniel Elkins, who possessed the weapon at the beginning of the series.
The gun used in the series is actually a replica Paterson modified to fire metallic cartridges. The gun was described as being built in 1835, before Colt made firearms, and fires metallic cartridges which were never made to fire in a Colt revolver until 10 years after Samuel Colt's death. 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. The props department also has a rubber version of the Colt to be used in fight scenes for pistol-whipping.