The Night Alien ship was a starship operated by the Night Aliens during the 24th century in a Delta Quadrant region dubbed "the Void," by the crew of the USS Voyager. Thousands of these ships were located in "the Void".
In 2375 the Voyager under the command of Captain Kathryn Janeway made first contact with the species after the ship had been boarded by seventeen of them. Tuvok modified a photon torpedo to use it as a light source and discovered three of these ships surrounding the Voyager.
After Captain Janeway and a wounded Alien made a "peace treaty" and the Alien was beamed back aboard one of the ships, Voyager went to a spatial vortex nearby which was used by the Malon Emck, to destroy it. The Malon used the Void as a garbage dump for their contaminated antimatter which caused theta radiation poisoning to the Night Aliens.