Nemex is a three-eyed, four-armed impish-looking creature of the Astral World. He has purple skin and white hair and speaks in a high-pitched rasping voice. He only appeared in one episode in the original ThunderCats series .
Nemex has two forms. The first is his 'normal' form in which he is short and skinny. However, when facing an opponent, he transforms into his second form whereby he grows into a muscular giant, almost three times his original height.
He also has the ability to shoot powerful energy beams from his eyes as well as his fingertips.
Nemex is the jailor of the Astral Prison and delights in taunting his captives and extracting any knowledge they may posses. His prisoners are doomed to remain in his captivity for all eternity. His guards patrol the prison and the moat surrounding the prison is inhabited by the fierce Astral Moat Monster which deters any and all intruders.
He attempts to enslave Jaga in the Astral Prison and to force him to give up all his knowledge, but Lion-O arrives in the Astral World and eventually defeats him using the Sword of Omens. Lion-O then frees Jaga and another prisoner, a wizard named Brodo who helps to transport Lion-O back to Third Earth .
- The Astral Prison (1st and only appearance)