Nostramo was the planet on which Konrad Curze, the Primarch of the Night Lords Legion was discovered. It was perpetual night on Nostramo and suicide rates and murders were frighteningly high. Unlike other Primarchs, Curze wasn't taken in, but had to fend for himself. With his enhanced body and mind, he quickly established himself as a major power in the cities of Prospero and thanks to countless atrocities commited by him, a semblance of law was imposed upon much of the area in which he lived. It is during this period that he earned the name "Night Haunter".
After the Horus Heresy, Curze returned to Nostramo with his Legion, gifted to him by the Emperor when he was eventually discovered, and destroyed it utterly with orbital fire from his fleet. This fulfilled his visions of seeing his planet being destroyed by beams of white light.