The Dark Heart was a ruin located deep within the twisted regions of the Nightmare Lands on Voss. Few surviving texts speak of the site as being a complex maze of chambers with some being sealed while others being broken from within. In addition, it was claimed that a vast series of underground corridors resided at the Dark Heart. It was said that the area was filled with corrupted monsters and ancient secrets with orbital reconnaissance indicating that it may in fact be the oldest structure on the planet.
The Sith Lord Nerrethel spent two years researching texts and studied the Dark Heart. His activities led to the formulation of several theories with one claiming that the architecture resembled that of the ancient Sith of Korriban. This included an orientation relative to Voss's constellations. Following an attempted visit to the Dark Heart himself, Lord Nerrethel was found dead on the borders of the Nightmare Lands with the only words of his expedition being "it sees".
- Star Wars: The Old Republic (First appearance)