- Complete Monster:
- Metlar is the tyrannical leader of the Inhumanoids. The former slave of Sslither, Metlar overthrows and imprisons his former master before waging a genocidal war against the Mutores to Take Over the World. Awakened from his seal eons later, Metlar launches an all-out attack on Earth with his fellow Inhumanoids, razing a Soviet weapons department to a smoldering heap and stealing several cluster missiles while having his servants attack and destroy all they can. Metlar's ultimate goal is to use the missiles to obliterate the crust of the Earth and drown the entire world in fire, killing everything—his own loyal servants not excluded—so he can rule over the ashes that remain. Throughout the rest of the series, Metlar brutalizes and threatens to torture his own minions for every slight and attempts to destroy everything he can get his fiery talons on.
- D'Compose, Metlar's terrifying second-in-command, is a hulking, undead monstrosity who pulled an entire city underground to turn it into his personal domain, killing everyone who lived there and reducing the city's knights into his undead slaves, cursed to wander the ruins of the town forevermore. Able to painfully transform anyone he touches into his undead slaves, D'Compose demonstrates his powers on the noble scientist Sandra Shore and tries to use her to kill her own friends, eagerly decomposing anyone he can whilst aiding Metlar in his conquest. D'Compose's vilest actions come when he has Blackthorne Shore amass countless disaffected teenagers into a cult in his name, reducing them all to his decomposed slaves and having them attack the nearby city, proclaiming his intention to shroud the world in darkness and turn all that lives into the undead.
- The aforementioned Blackthorne Shore is a wealthy industrialist who came across the secrets of the Inhumanoids. Blackthorne attempts to free them to use them to take control of the world, allowing them to first wreak death and destruction at their whim. When his own sister Sandra is turned into an undead monster by D'Compose, Blackthorne acts horrified—but then abandons the heroes to die when they try to save her so he can take control of Metlar, settling for allying with him to present him with a way to destroy most of the world so Blackthorne can rule over the remainder. After being foiled, Blackthorne eventually starts a cult with D'Compose, convincing numerous young men and women to submit themselves to the evil Inhumanoid to be changed into his undead slaves. Blackthorne continues to try to control the Inhumanoids and kill the heroes in his quest to dominate the world, fully admitting that he himself is an utterly evil, monstrous human being as wicked as any Inhumanoid.
- Genius Bonus: The three Inhumanoids represent all three of the scientific "kingdoms", and these three kingdoms arguably help define the Inhumanoids' respective roles.
Mineral: Metlar. Since the planet itself is made of various mineral substances, it makes sense that he's the leader.Animal: D'Compose. Quite a few animal species are at least somewhat intelligent, so it makes sense that he's intelligent as well, making him Metlar's Dragon.Vegetable: Tendril. No plant species are known to have any intelligence as we understand it. In fact, the term "vegetable" is often used to describe a person whose higher brain functions have stopped. It wouldn't make sense for Tendril not to be a Brute.
- Playing Against Type: Dr. Derek Bright, mechanical master and general badass, is voiced by Richard Sanders- Les Nessman.
- What Do You Mean, It's for Kids?: It is, despite being violent and dark.
- Particularly any episode focused on D'Compose's signature touch of undeath.
- The Woobie: Tendril in "Primal Passions". He may have been evil, but Earth Corp pulled a pretty mean move on him.