Sigils and Symbols
Angel Banishment Symbol
Episode(s): Heaven and Hell, The Rapture, Lucifer Rising, Sympathy for the Devil
Drawn in blood, the banishment symbol will temporarily banish angels (excepting the one who drew it). Castiel has used it several times as have Anna and Dean.
Blue Öyster Cult Logo
Episode(s): Hell House
Although usually recognised as the logo of heavy metal band Blue Öyster Cult, the symbol traditionally belongs to Kronos, the king of the Titans from Greek Mythology and is also the alchemical symbol for lead - one of the heaviest metals. It was used as one of the symbols drawn on the walls of the Hell House, probably copied from the cover of a Blue Öyster Cult LP.
Sue Ann LeGrange was using a Coptic Cross to control a Reaper. In Christian mythology, the cross represents Christ's crucifixion and resurrection, which explains why it was being used in connection with a reaper.
Episode(s): Devil's Trap, Crossroad Blues, Born Under a Bad Sign, All Hell Breaks Loose Part Two, The Magnificent Seven, Bad Day at Black Rock, Sin City, Jus In Bello, No Rest For The Wicked, Are You There God? It's Me, Dean Winchester, Metamorphosis, On the Head of a Pin, When the Levee Breaks, Sympathy for the Devil
The Devil's Trap is primarily used to control demons. When they step onto or under a drawn trap, they are powerless and unable to move. Once trapped, they can easily be exorcised. In addition, a Devil's Trap can be drawn or engraved onto an item in order to protect it from demons. The first image is the standard trap that is used for demons. The second image is a variation that Sam drawns on the trunk of the Impala in order to make it into a safebox that cannot be accessed by demons.
Episode(s): Sympathy for the Devil, Good God, Y'All
In order to protect Sam and Dean from the angels that are trying to stop them, Castiel engraves a series of symbols on the boy's ribcages. The sigils also hide them from Castiel, but can be seen on an x-ray. Click here for details on the inscriptions as translated by BloggingChick.
Episode(s): Pilot, Dead Man's Blood
First seen when worn by Amy while she talks to the boys about her boyfriend having gone missing. She says that she wears it to scare her parents with "all that devil stuff". This is a common misconception about the symbol which is traditionally a pagan protection symbol. However, certain malevolent practices, such as Satanism, have been known to use the symbol for their own purposes, usually inverting it so that the fifth point is downwards. It symbolises the four elements (earth, air, fire, water) plus the addition of spirit as the fifth point. There is also a pentagram etched onto the butt of the Colt.
In its simplest form, a quincunx is simply the arrangement of five units in a pattern like the five-spot on a dice - one unit in each corner and one in the centre of them. In the show, Sam identifies it as being a hoodoo symbol which, when combined with bloodweed can become a powerful charm to ward off enemies. According to the Pad of Definitions on the WB website, a quincunx "is often used in Hoodoo as a sort of 'artifical crossroad' and can be created inside a room in the house. The quincunx or five-spot is generally used for scaling and fixing spells in place.".
Sigil of Azazel
Episode(s): In My Time of Dying
Used by John Winchester to summon the Yellow-Eyed Demon. John's use of the sigil indicates that he was aware of the demons true identity as Azazel.
Episode(s): Jus In Bello, The Monster at the End of This Book, Lucifer Rising
Dean and Sam reveal that they both have matching tattoos, designed as protection charms to prevent possession. When asked how long they've had them, Sam responds "Not long enough" - a reference to his possession in the episode Born Under A Bad Sign.