In the mirror universe, K'muc was a Klingon captain in the Klingon-Cardassian Alliance. In 2371, commanding the Imperial Starship Mek'leth, he confronted a Borg diamond that had destroyed a Klingon outpost near Carraya IV. Refusing to believe that resistance was futile, K'muc fought valiantly, but the Borg quickly adapted to the Klingon weapons. The Borg surgically dismantled the Mek'leth with tractor beams, killing K'muc and his subordinates. (TNG novella: The Worst of Both Worlds)

K'muc was probalby the first Klingon to make official contact with the Borg Collective in the mirror universe.