Dark Mark (sign)

"...You-Know-Who and his followers sent the Dark Mark into the air whenever they killed. The terror it inspired...you have no idea, you’re too young. Just picture coming home and finding the Dark Mark hovering over your house, and knowing what you’re about to find inside... Everyone’s worst fear...the very worst."

- Arthur Weasley

The Dark Mark is the symbol of Lord Voldemort and his Death Eaters. It refers to the symbol conjured in the air by the spell Morsmordre.

Appearance
The Dark Mark appears as a skull with a snake protruding from its mouth. This might have been inspired by the hiding place of the Basilisk in the Chamber of Secrets. When summoned, the basilisk would emerge from the mouth of Salazar Slytherin. The serpent is also the symbol of Slytherin house, and thus appropriate to be used by the Heir of Slytherin. The symbol might also be related to the fact that Lord Voldemort was a Parselmouth, a gift he thought made him un-like the rest of the wizarding world. The Dark Mark on the forearm is black, while the Dark Mark conjured by Morsmordre is green.

In the Sky
As a signature of their work, the Death Eaters can also use a spell to create an image of the Dark Mark in the sky. The incantation of this spell is Morsmordre. The appearance of the one in the sky is basically the same as the one on the forearm, but green in colour. Notable uses include in the woods during the 1994 Quidditch World Cup Final, when it was cast by Barty Crouch Jr., and over the Astronomy Tower of Hogwarts School of Witchcraft and Wizardry by Gibbon in 1997.

The other form of the Dark Mark has been seen when Voldemort touches the Dark Mark branded on an arm, a skull forms in the sky above and the alerted Death Eaters apparate out of its mouth instead of a snake.

Known Occurrences

 * Quidditch World Cup
 * Astronomy Tower

Behind the scenes

 * The Dark Mark in the sky and on the Death Eater's arms are different in appearance. The one in the sky is plainly a skull with a snake coming out straight out of its mouth, while the tattoo branded on Death Eater's arm is much more intricate and detailed, the snake being much longer and winding..
 * In Harry Potter and the Half-Blood Prince, the Dark Mark is cast by Gibbon in order to lure Dumbledore to the Astronomy Tower. In the film version, the Mark is cast by Bellatrix Lestrange in celebration after Dumbledore's death.
 * In the beginning of the fourth film, the skull and snake appear as a green glowing light, while later in the same film and twice in the sixth film, the skull is moulded from the clouds. There also seems to be no serpent jutting out of the mouth of the skull. Death Eaters are also shown Apparating out of the skull's mouth.

Notes and references
Marque des Ténèbres Тёмная метка