The Chimeras are minor antagonists that only appeared in the episode Samurai Vac. They are three-headed mythological beasts. Each of their heads are of different types of animals such as lions, birds, goats, and snakes.
The two Chimeras, Yellow, and Green, his father, debuted and only appeared in "Samurai Vac" as the semifinal main antagonists.
After a while, Yellow (now looking blue) managed to return with another much larger Chimera, his father, Green. Jenny was eaten and spat out by Green, leaving only Samurai Vac to stop the two Chimeras. Vac used his vacuum abilities to tickle Green, causing one of his heads to laugh and involuntarily breathe fire, scorching himself. This caused the citizens of Tokyo to laugh at the Chimeras, and the monsters fled in shame.
Yellow and his father, Green, are the semifinal villains of the entire series.