The Endarkened, also known as Endarkened Ones or Dark Shadowhunters, were Nephilim who became corrupted after drinking a mixture of the blood of the Greater Demon Lilith and the blood of Sebastian Morgenstern from the Infernal Cup.
Those who drank from the Infernal Cup gained superior strength and agility compared to most Nephilim, as a result of their alliance being changed from angelic to demonic. For the same reason, the Endarkened were unable to use seraph blades, which call upon the name and spirit of angels; their angelic runes also faded from their skin. Instead, the Endarkened Nephilim could only bear demonic runes.
In accordance with Nephilim society, these dark Shadowhunters wore red gear and bore red runes, symbolic of the "ceremony" held, or the change they underwent, when the Shadowhunters became Endarkened.
Since their lives were bound to the Infernal Cup, its destruction caused the deaths of every single one of the Endarkened it created.
- Despite the best efforts of the Silent Brothers, and the warlocks of the Spiral Labyrinth, no cure was found that could transform an Endarkened warrior back into Nephilim.
- If any of the Endarkened drank from the Mortal Cup, they would die instantly, as was the case with Amalric Kriegsmesser.