Karn is a son of Mannan and has lived almost since the beginning of time. He is much older than the Wild Hunt, and much more powerful. In the old days he hunted giants and monsters with his siblings, but chose to serve the Unseelie King as one of his assassins.
In 2012 Karn and his siblings were sent after the Blackthorn family to retrieve the Black Volume of the Dead for the Unseelie King. Karn went after Kit Herondale and the twins Ty and Livvy Blackthorn in London, along with Etarlam and Eochaid.
In London Karn fought Kit and the twins alongside his siblings until the fight was interrupted by Gwyn ap Nudd and Diana Wrayburn. He was shocked when Eochaid proclaimed that their brother Fal was dead, and swore to repay Gwyn for his treachery before leaving with his brothers to join their siblings in Cornwall.
Karn later joined his surviving siblings in attacking the London Institute. He was fearful of Emma Carstairs' sword Cortana, recognising it as a blade forged by Wayland the Smith, but attacked Emma anyway and fought until Annabel Blackthorn appeared and threatened to reveal the Unseelie King's name. Karn then retreated with his family.
Like all the Riders of Mannan, Karn is arrogant and confident in his abilities. He has no problem killing and seems to enjoy carrying out his missions.
Karn, unlike his siblings, has short bronze hair in curls that make him resemble a Greek kouros. He is beautiful, with a cruel and lovely face covered in a bronze half mask, and wears the typical bronze cloak and armor etched with designs of waves and the sea. He also wears longsword at his side.
- Longevity: As a Rider of Mannan, Karn is very old and has been alive for thousands of years.
- Enhanced Strength/Speed: Karn is able to move incredibly fast and deal heavy blows.
- Invulnerability: Karn is immune to most magic, such as seraph blades, and cannot be killed by conventional means.
- Lord of Shadows (first appearance)