The Druoda were a Delta Quadrant species capable of building extremely powerful long-range weapons controlled by artificial intelligences, such as the series 5 long-range tactical armor unit.
Its military command was called Strategic Command Matrix.
Until 2372, they were engaged in war with another space-faring species from the Delta Quadrant who maintained a military installation on Salina Prime. (VOY: "Warhead")
This species was only mentioned in dialogue.
The Druoda script on the warhead was designed by Wendy Drapanas. (Star Trek: The Magazine Volume 1, Issue 7, p. 24)
According to Star Trek: Star Charts (p. 91), there was a star system named Druoda, which might possibly be the system of origin for this species, in the quadrant. The system's primary was a K-class star.