Nihydron

From Memory Alpha, the free Star Trek reference.

In one possible timeline, the Nihydron are a space-faring species native to a region of space near the Krenim Imperium. In 2374, three Nihydron warships joined the USS Voyager in its attack on the Krenim weapon ship. B'Elanna Torres and Harry Kim were assigned to work with the Nihydron to implement temporal shielding aboard their ships. (VOY: "Year of Hell, Part II")

The current state of the Nihydron Empire is unknown, after the temporal weapon ship was erased from time, undoing all the damage it had done.