King Koil is a titular minor antagonist of the reboot TV series, Ben 10. He first appeared in the episode, King Koil.
When Ben and Gwen were sent to the reptile dome, King Koil appeared and he even controlled the reptiles around him. He is using them to fight Ben and Gwen. Ben remembered that in the song, reptiles can only see heat, so he transformed into Diamondhead and he appeared invisible to King Koil, since Diamondhead does not have heat. Ben defeated King Koil.
All Koiled Up
King Koil returned, but this time, he is riding a giant monitor lizard, who is being mind controlled by him. He accidentally sat on the throne and people are amazed and he liked how he treated as a king based on his egotism. Ben lated defeated him.
King Koil appeared as a humanoid reptile with blonde hair. He also appeared to have eight limbs, unlike other reptiles. He also wears a black cape.
King Koil is an egotistic type, who wanted to rule.