The Dark Mark

• Type: Magical Brand / Summoning Sign
• Owners: Lord Voldemort, Death Eaters
• Maker: Lord Voldemort

The Dark Mark exists in two distinct forms: a physical brand on the forearm and a magically conjured sign in the sky.

• The Physical Brand: This is a mark magically burned into the skin of a Death Eater's inner left forearm. It appears as a vivid red, tattoo-like image of a skull with a large serpent issuing from its mouth like a tongue. When inactive, it can resemble a faint scar. When activated by Lord Voldemort, it turns jet-black and burns, signaling a summons.
• The Conjured Sign: Cast using the incantation Morsmordre, this version of the Dark Mark is a colossal, glittering green skull formed of what appears to be emerald stars. A serpent likewise protrudes from its mouth. It hangs eerily in the sky, a terrifying beacon announcing a Death Eater's presence, often after they have committed a murder.

The Dark Mark serves primarily as a symbol of allegiance to Lord Voldemort and as a powerful magical tool for his Death Eaters.

• Summoning Device: The physical mark connects every Death Eater to their master and to each other. By pressing his finger to any single Dark Mark, Lord Voldemort can send a burning, summoning sensation to all of his followers, who are expected to Disapparate and Apparate to his side immediately. This is first explained by Lord Voldemort himself in the Little Hangleton graveyard.
• Indicator of Voldemort's Power: The brand on a Death Eater's arm darkens and becomes clearer as Lord Voldemort's power grows. Igor Karkaroff grows increasingly panicked as his mark becomes more defined, and Severus Snape shows his own darkening mark to Cornelius Fudge as proof of Lord Voldemort's return.
• Psychological Warfare: The conjured Dark Mark has no known direct offensive capability, but its primary function is to inspire terror. During the First Wizarding War, the sight of it was enough to make witches and wizards flee in panic. It serves as the Death Eaters' calling card, most often cast over a house or building where they have murdered someone.

The Dark Mark was invented by Lord Voldemort during his initial rise to power and was used extensively throughout the First Wizarding War as his symbol. It became synonymous with terror and death. After Lord Voldemort's first downfall, the marks on his followers' arms faded to scars, barely visible. They began to darken again as he regained strength, a fact noted with terror by Igor Karkaroff and used as evidence by Severus Snape. The first time the Dark Mark is seen in the series is when it is conjured by Barty Crouch Jr. at the Quidditch World Cup using Harry Potter's stolen wand. The appearance of the mark causes mass panic among the witches and wizards in attendance. Later, in the graveyard of Little Hangleton, the newly-restored Lord Voldemort touches Peter Pettigrew's mark to summon the Death Eaters, demonstrating its primary function. One of the most significant uses of the conjured mark was when it was cast over the Astronomy Tower at Hogwarts Castle following the death of Albus Dumbledore, signaling a major victory for Lord Voldemort and his followers.

The Dark Mark is a recurring and powerful symbol of Lord Voldemort's evil and the loyalty of his followers. It represents the permanent and inescapable bond a Death Eater has with their master. For characters like Draco Malfoy, receiving the mark signifies his forced entry into true darkness and the immense pressure placed upon him. For Severus Snape, the mark is a constant reminder of his past but also a crucial element of his role as a double agent, as it grants him access to Lord Voldemort's inner circle. Throughout the series, the appearance of the mark, whether on an arm or in the sky, signals immediate danger and the presence of Dark Magic. It functions as a constant, visible threat that hangs over the wizarding world during Lord Voldemort's reign.

• The incantation used to conjure the Dark Mark, Morsmordre, is explained to mean “take a bite out of death” in French (mors, 'death' and mordre, 'to bite'), fitting for followers who call themselves Death Eaters. (J.K. Rowling interview)
• In the film adaptations, the physical mark is often depicted as a more intricate, blackened brand, sometimes appearing animated on the skin. The conjured mark is a large, swirling cloud of dark smoke that resolves into the skull and serpent image. (film)
• The skull and serpent imagery is a direct reference to Salazar Slytherin, the founder of Slytherin house and ancestor of Lord Voldemort, who was famous for his ability to speak Parseltongue.