Hur'q

The Hur'q were a race of aliens who once invaded Qo'noS. When they were forced out, they took with them many Klingon treasures, including the Sword of Kahless. The word Hur'q later became the word for "outsider" in Klingonese. (DS9: "The Sword of Kahless", The Art of the Impossible)

Gothmara used Hur'q DNA to create a personal army, which she used to overthrow Martok in 2376. (The Left Hand of Destiny, Books 1 and 2)