Ship of the Turei, who controlled the underspace corridors of the Delta Quadrant and attacked Voyager to stop it learning their secrets in Dragon's Teeth.
Turei ships ruled a network of underspace corridors that allowed travel across vast distances in minutes. In Dragon's Teeth, a Turei ship pulled Voyager out of a corridor, then demanded that the crew erase their data about it, and when Janeway refused, the Turei attacked and called for reinforcements.
Voyager hid on a radiation-shrouded planet, where it found and awakened the Vaadwaur, old rivals of the Turei who had once controlled the corridors before their defeat nine centuries earlier. The Turei feared the Vaadwaur's return and kept pursuing them both.