Idrin was an Alpha-Hirogen hunter in the 24th century.
In 2374, Idrin contacted the USS Voyager and ordered to discontinue their use of the Hirogen communications network. Captain Kathryn Janeway tried to negotiate with Idrin but without any result. Seven of Nine decided to send a feedback surge and shocked the Hirogen to make him unconscious. (VOY: "Message in a Bottle")
Idrin later captured Tuvok and Seven of Nine as they were trying to download messages from Starfleet Command from a Hirogen relay station. He decided to gut the two and use their skeletons as trophies. Voyager located his Hirogen ship and by boosting the effect of the quantum singularity that the Hirogen's used as a power source, they were able to beam Tuvok and Seven aboard Voyager, as the Hirogen ship fell into a black hole. (VOY: "Hunters")