The quarter of the Milky Way galaxy appearing to be located between 12 and 3 o'clock if the great plane of the galaxy is viewed as a clockface and the 6 o'clock position bisects the Sol system.

Although it was known to be home to the Borg, the Delta Quadrant had been wholly unexplored until word was received in 2374 from the lost U.S.S. Voyager. Compressed messages from the ship, long presumed a casualty, detailed its accidental arrival there and travels homeward among cultures such as the Kazon sects, the Vidiians, Talaxians, Ocampa, the Hirogen, Species 8472 — and, of course, the Borg.