The Dark Nebula is a nebula located in an unknown sector of the galaxy. Presumably it's a rather dark place. The nebula is inhabited by Dire Wraiths and as a result, space travellers usually steer away from it.
Such was the Dire Wraiths' association with this nebula that after their homeworld was destroyed, Krok identified one as simply coming from the Dark Nebula. Krok also identified the Wraiths' presence in the nebula as the reason Megatron avoided it during the Great War.
A fleet of Worldsweepers known as the "Phantom Fleet" went missing in the Dark Nebula during the war.
- The Dark Nebula was the Wraiths' point of origin in the original ROM, Spaceknight comic series, and was established to exist in the Hasbro Universe in the The Transformers: More Than Meets The Eye Revolution tie-in, though it's not clear if IDW's Dire Wraith homeworld exists within it.
- Coincidentally, Transformers in the 1980s also had a Dark Nebula in the Transformers: Victory anime, and appropriately the two concepts were merged together for the Hasbro Universe.