The Snake Men were released later in the original franchise's run, and there was considerable retconning to work the characters into the existing Masters of the Universe mythos.
In the distant past, the Snake Men were a vast, ruthless army that conquered numerous worlds, and served an evil ruler named King Hiss. Hiss and the Snake Men tried to conquer Eternia, and created Snake Mountain as their base of operations. However, the Elders of Eternia proved too powerful for the Snake Men and used their magic to cast Hiss and his army into a limbo-like dimension. This caused the empire of the Snake Men to collapse, although a small number of them remained on Eternia. Eventually, Hiss is set free by Skeletor, who had made Snake Mountain his base.
Hiss and Skeletor form an uneasy alliance against He-Man, the greatest opposition to their mutual dreams of conquest. Skeletor's Snake Man minion, Kobra Khan, serves as his ambassador to King Hiss. Together the two villains are able to trap He-Man. They attempt to use their combined magic to pull the entire Snake Man army back into Eternia, but even their combined magical abilities united are only strong enough to return two snake soldiers: Tung Lashor and Rattlor. Realizing that they need more potent magic to resurrect the entire army, Hiss and Skeletor take He-Man's Power Sword, and attempt to use it to summon forth all the Snake Men. However, He-Man is able to free himself and recover his sword, foiling the return of the reptilian hordes.
Despite their initial failure, King Hiss and Skeletor move forward with their plans of conquest. The two villains once again combine their magic to raise three great towers that had been buried eons ago by the Elders of Eternia. The Elders had sunk the towers below the earth to ensure that they would never fall into the hands of the Snake Men or any other evil forces. The three towers were Grayskull Tower, which possesses the power of good, Viper Tower, possessing the power of evil and Central Tower which possesses the power of both. Hiss and Skeletor both secretly plan to betray each other once they have taken control of the towers. Though Skeletor is unable conquer Central Tower, a feat which would have given him the power of all three towers, King Hiss is able to seize Viper Tower. Using the magic of Viper Tower he is able to transport two more Snake Men from limbo, Snake Face and Sssqueeze.
Not long after, in a battle in Viper Tower, He-Man turns all the Snake Men into stone, by reflecting Snake Face's power of petrifaction back at them. Snake Face and Sssqueeze appear in the later minicomic "Energy Zoids".
Later He-Man and the Sorceress venture into Eternia's past, to the time when the Snake Men originally invaded Eternia. Witnessing the Snake Men terrorizing a village He-Man wants to step in, however the Sorceress prevents him, as his interference could alter history. However, unbeknownst to the Sorceress, Skeletor had followed them through the time stream. Upon arriving he joins forces with King Hiss, saying that he wishes to help them and that his magic powers could help destroy the Elders. King Hiss accepts Skeletor offer and thinking to himself "Perhaps this is an emissary from the Unnamed One whom we serve" (the full meaning of this statement is never disclosed during the vintage era). The Snake Men rode into battle on the backs of mechanically augmented dinosaurs.
Seeing that Skeletor had entered the past, the Sorceress decides that it is necessary for He-Man to become involved, disguising him with her magic, she sends He-Man into battle against Skeletor, King Hiss and the Snake Man army. However, before the battle can conclude a shadowy figure, He-Ro, intervens. Using magic he hurls Skeletor, the Sorceress and He-Man back to the future. The final fate of the Snake Men is never revealed, as the Masters of Universe toyline and its accompanying mini comics came to end.
None of the Snake Men are featured on Filmation's animated series, with the exception of Kobra Khan, a snake figure in Skeletor's service introduced earlier in the franchise's run. When the Snake Men were introduced, Kobra Khan was said to be a go-between, working for both Skeletor and King Hiss.
The cartoon series had ceased production before the Snake Men could be introduced. Two Snake Men, Rattlor and Tung Lashor, were adapted to appear in the spin-off She-Ra: Princess of Power series, where they worked for Hordak as members of the Evil Horde, portrayed as generic warriors with no nod to their Snake Men origins. Tung Lashor, simply called "Tung" in some appearances, in particular bore little resemblance to his figure version, and inexplicably, is seen to be working for Skeletor in one episode, despite still wearing a Horde emblem.
The Snake Men play a large role in the second season of the Mike Young Productions cartoon series. Upon re-runs, the second season was renamed Masters Of The Universe Vs The Snake Men. They are a diverse group led by King Hiss, who prove to be as much a danger as Skeletor, in fact, Skeletor only makes three appearances through the entire story arc. Similar to the old story, the Snake Men are an ancient threat that plagued Eternia in the distant past until they were locked away in the void by the power of the Elders. The threat of the Snake Men was so ancient that in a way it predated the creation of the Elders themselves during the time of King Grayskull who fought against this menace. However, in this new version, they are presented as a very strong army, who, as well as taking on He-Man, are also at war with Skeletor instead of forging an alliance with him.
- King Hiss: Leader of the Snake Men, can shed his humanlike "skin" to become a mass of snakes from the waist up.
- Rattlor: Possesses an extending neck, and rattling tail. He appears in the She-Ra: Princess of Power animated series as a member of the Evil Horde, and in the 2002 animated series, where he is presented as the head of the Snake Men army trying to release their leader, King Hiss.
- Tung Lashor: Possesses a super long extending tongue. He appears in the She-Ra: Princess of Power animated series as a member of the Evil Horde and in the 2002 animated series. The original He-Man cartoon had ceased production when his figure was released.
- Kobra Khan: His character pre-dates the introduction of the Snake Men, formerly working solely for Skeletor, where he sprays a "hypnotic" mist. He appears in the He-Man and the Masters of the Universe animated series as one of Skeletor's Evil Warriors, in which he sprays a sleeping gas, and on one occasion is shown to have stretchable arms, similar to the Sssqueeze character, subsequently as a 'go-between' in other material. He appears in the 2002 animated series, in which he sprays acid, and is more loyal to his fellow Snake Men.
- Sssqueeze: Possesses super-long bendable arms. He only appears in the 2002 animated series.
- Snake Face: Snakes extend from his face and shoulders to "petrify" opponents. He only appears in the 2002 animated series.
- Fang-Or: The Snake Men's mechanical expert. He debuted in the Masters of the Universe Classics toyline.
- Terroar: A formless exile from Melodian who assimilated the characteristics of the Evil Warriors, the Evil Horde, and the Snake Man upon arriving on Eternia. Terroar was taken in by the Snake Men when King Hiss was impressed with his sonic shriek that brought all three of his pursuers to their knees. He debuted in the Masters of the Universe Classics toyline.
- Lord Gr'asp: The Snake Men's master strategist. He debuted in the Masters of the Universe Classics toyline.
It is reveal in a MOTUC Collector's Choice bio that the Repton are indeed, the descendants of the Snake Men.