In the supernaturalSupernatural series, we find out about 'The Colt', a special gun, as John WinschesterWinchester puts it:
John Winchester
Back Back in 1835, when Halley's Comet was overhead, 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. Story goes, he made thirteen 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.
Supernatural Season 1, Episode 20 - Dead Man's Blood
However, Compare and Contrast with:
LUCIFER
Don't feel too bad, Sam. There's only five things in all of creation that that gun can't kill, and I just happen to be one of them. But if you give me a minute, I'm almost done.
Supernatural Season 5, Episode 10 - Abandon All Hope
Clearly one of these five is Lucifer, but it's not clear if this is him specifically (so that the apocalypse can happen?) or all archangels? If the laterlatter, does that mean that the angel knives can kill what the colt can't (Gabriel)?
The only other two I could think of is God, and Death.
Who else is on this list, and is it individuals or types of creature?