The Dragon King's Army was the army of Onaga, the former emperor of Outworld in the Mortal Kombat game series. Long ago when he ruled Outworld, the Dragon King commanded an army of loyal and disciplined warriors which were said to be unbeatable, having won every battle they fought in. In truth, however, Onaga's soldiers were only "invincible" because Onaga would constantly resurrect them during battles. Whenever a soldier was killed, Onaga would simply cast his magic to reanimate the corpse and it would continue to fight.
After Onaga was assassinated by Shao Kahn, his army was buried in his tomb with him. The soldiers remained standing in vigil over the Dragon King's sarcophagus in a mummified state for thousands of years until the tomb was discovered by the Netherrealm sorcerer Quan Chi. Quan Chi sought to use the army himself to carry out the conquest of the realms, and formed an alliance with Shang Tsung so that he could take advantage of Tsung's soul manipulation talents. By transplanting the souls of slain warriors into the mummified soldiers, the Deadly Alliance succeeded in reviving the Dragon King's army. They never had the chance to lead the army, however, as Onaga had returned from beyond death to reclaim his empire. Onaga would lose the army as well since Raiden released his godly energy in a tremendous magical explosion that destroyed the army completely.