The Serpent Men are a race of snake-like humanoids, said to be the children of Set himself. As such, they are his followers, servants, and soldiers, and were given the power to appear in human form and worm their way into positions of power as spies, infiltrators, and even usurp human identities. It is worth noting that Serpent Men and humans can interbreed with each other as demonstrated by Jasmine's mother becoming pregnant by a Serpent man.
The Serpent Men however are vulnerable to the magic of Star Metal, which glows blue in their presence, can dispel their human disguises, and banish them to the Abyss.
Thry are led by the dark wizard Wrath-Amon, the chief servant of Set.