The Vek was a civilization from the Alpha or Beta Quadrant which was at war with the people of Minnobia as of 2373.
In that year, Quark claimed that Hagath and Gaila's supplier had sold every stockpile of a mutagenic retrovirus to Minnobia to be used against the Vek. (DS9: "Business as Usual")
This species was only mentioned in dialogue.