The Alien Mastermind: Sosai X
Overlord X/Overlord Z
Sosai X is often translated as "Generalissimo" or "Overlord X." In some versions, he is, for all practical purposes, a god; in others, a computer. (In the OAVs, he's a godawful computer-generated thing, but a vicious godawful computer-generated thing.)
In the original Gatchaman series, he is an alien from the planet Selectro, and he appears as a vague bluish diamond flame with slitted eyes and something that more than just resembles a tongue smack in the middle of his forehead. (Some people think he looks like a chicken. I still can't see that. I don't want to see that.)
He seems to reside on some kind of fiery background in a huge computerized control room, but he can manifest outside of this screen, as we see when he comes to Katse's rescue when Ken unmasks Katse for the first time. When, at the end of Gatchaman I, he learns that his home planet Selectro has exploded, he tears himself out of the control room, and we see a huge glowing gold pillar.
In Gatchaman II, he has a new control room with a new screen, but he's more of a rippling image than a flame, and he is surrounded by spinning bands of light.
He is destroyed at the end of Gatchaman II, but he's able to regenerate himself from a fragment of the remains; the new creation calls itself Z.
He is protective of his commanders, though he often fails to come to the rescue unless death is imminent. He almost seems to look upon his commanders as pets. He put a lot of work into training them, but they're replaceable.
Obviously, he has a lot of odd knowledge if he's capable of merging fraternal twins into a single being and aging adorable children into malicious adults. Sometimes he seems little better than a malicious child himself. When Count Egobossler and the rightful heir to his throne reach a point where they must battle it out, Sosai Z sits back and watches the fun instead of leaping to Egobossler's aid.