Dark Riders of Acherus

The Dark Riders of Acherus (also referred to simply as the Dark Riders) are a sub-group of the Death Knights of Acherus and later the Knights of the Ebon Blade. They are led by Salanar the Horseman.

They live in the Realm of Shadows. When a horse is sent there, they slay it and raise it as a deathcharger.

The order is potentially old, as Dark Rider Ghrave has been described as "ancient".

They have their own sigil.

Trivia

 * Attumen the Huntsman and the Ghostriders of Karabor use the same model as them.
 * Prior to the Shadowlands expansion, the Realm of Shadows where the Dark Riders of Acherus were present was considered as a part of the Shadowlands, but is now confirmed to be the Veil.

Speculation
Darkrider Arly could be a member of their ranks.