As ruler of the Snake Men, King Hiss has a vast and ruthless army at his command. In the distant past they have conquered numerous worlds including Eternia. But they were defeated by Hordak with his own great army who had also planned on conquering the various worlds. King Hiss once again tried to conquer Eternia after King Grayskull's defeat at the hand of the Horde. Yet again he failed. However, as a punishment the Elders of Eternia used their vast powers to cast his army of Snake Men into a limbo-like dimension. King Hiss himself was sealed beneath his base, Snake Mountain, which he'd had constructed by Zodak after devouring Zodak's brother.
Over time, the base was taken over by Skeletor and it became the base for his forces. The few remaining Snake-Men who had not been imprisoned in the limbo-like dimension joined Skeletor; one of them was named Kobra Khan, a passionate follower of King Hiss. Soon he discovered where King Hiss had been sealed away, and with another Snake-Man named General Rattlor they freed their King from his confinement with use of Zodak's cosmic staff. After being freed King Hiss defeated Skeletor and his minions. He took back control of his base, but also accepted Evil-Lyn as a new follower, even though she remained a minion of Skeletor. Now free he used his own magical powers to release his vast army from their prison in the limbo-like dimension that they were once sealed in. With them free, he began his plans to conquor all of Eternia.
During his conquest of Eternia, King Hiss battled with the great hero He-Man and the other Masters of the Universe. Eventually he was defeated. King Hiss’ army was in ruins, leaving only a handful of Snake-Men to do his bidding. In a desperate attempt to conquer the world, he released the Snake God from its prison. With its help he set his sights on Castle Grayskull. Outside of the Castle, He-Man battled with the Snake God while Zodak battled King Hiss. He-Man and Zodak were both victorious, as a result the Snake God itself summoned the power of Grayskull and was imprisoned back into limbo. King Hiss was defeated & lost vast amounts of his powers.