A while ago I made a post asking if anyone watching the new CGI Masters of the Universe show was interested in info-posts on King Hiss from previous iterations of the franchise. Most people said, 'yes'.
King Hiss is the leader of the Snakemen
He first appeared in 1986 in the mini-comics and a corresponding action figure.
He was sealed under Snake Mountain at some point during the Great Wars of Preternia, before the sinking of the Three Towers; but was released by Skeletor.
The first impression he gives is that of a handsome and heroic looking human. A disguise that fools both Skeletor and later He-Man.
During production of his character, it was discussed that the purpose for his "heroic human" disguise was specifically to fool He-Man so that he's caught off-guard when Hiss attacks. He hides in plain sight and strikes when least expected like a viper in the grass.
Hiss is still King of the Snakemen in the 2002 reboot. He was still sealed in a magical prison under Snake Mountain (the Void) during the Preternia era. He still has a human form and sheds his skin to reveal a body made of snakes.
But the 200x continuity gave more layers to his character.
King Hiss isn't just evil for the sake of evil anymore. Now he has motivations.
200x King Hiss loves his people, the Snakemen. But the only Snakemen left in the world are those who were sealed away with him and are now released, and the hybrid descendants of the Snakemen like Kobra Kahn. In one episode, Hiss tries to restore his people by using an ancient totem to transform all other races on Eternia into Snakemen. In another episode, he successfully revives the Snakeman goddess, Serpos, and beseeches her to destroy all non-Snakeman life on Eternia so his people can start over. (Both attempts are stopped by He-Man.)
Hiss has a very small part in the Classics-Line Comics from the 2010s. And, honestly, compared to how amazing they made him in the 2002 cartoon, its actually kinda sad.
It an time-travel issue, we see Hiss in the Preternia Era commanding the Snakemen and being the leader they all love and respect him for being.
But then he's betrayed and defeated by a time-displaced Skeletor.
The next time we see King Hiss, he's in the background of the Second Ultimate Battleground, standing next to Hordak.
We don't really get to see him fight, however, as the focus of the Battlegrounds are always on other character.
Hiss then dies, killed by Orko, when Orko used the Tablet of Separation to separate the souls of the Snakemen from their bodies, essentially wiping their whole race off the face of Eternia. (Yes, out of all the evil villains in the MotU franchise, Orko was the character who committed mass genocide. ...but that's a whole other post.)
We don't see Hiss again until the Fall of Eternia arc, and even then, he only appears on one page!
Apparently, Hiss, King of the Snakemen, was really just a servant of the Unnamed one all along. And the Unnamed One revives King Hiss from the dead-
-tells him he did a bad job-
That's it. That's King Hiss' final appearance in the Classics-Line comics.
Like I said, compared to the BAMF he was in 200x, the Classics-Line comics do him dirty!