Spectral Stalkers (Fighting Fantasy 45)
Globus is an archmage on the Ziggurat World who has summoned the Spectral Stalkers to find the Aleph, a powerful magical artefact that can transport its bearer to any time and place. With it, he will attempt to conquer the Macrocosmos.
Globus does not have any influence in any of the other worlds you come across in the Macrocosmos, but he does have an entry for him in the Directory of Wizards in the library of Limbo. When you get to the Ziggurat World, you will find that he is its ruler, known to and hated by all that he rules over. 9/10
You do not see any stats for Globus, but seeing as he places himself in an almost impenetrable giant crystal, I can't imagine that his skill and stamina are too high. That said, he has placed himself in an almost impenetrable giant crystal, so you can't actually kill him. 8/10
Globus looks down on those petty villains who want to conquer a mere world as he wants to rule the whole Macrocosmos. He truly is aiming for the Moon. And all the other planets. 11/10
He pretends to be all luvvy duvvy and nice but in fact he is really really evil. He also has some cool killer servants and lives on a giant Ziggurat. 7/10
He's under no illusions that he is anything but a tyrannical ruler. He is also smart enough to know that because of that, most people want to kill him. And also, he is not so vain that he thinks that people who hate him will fear him so much that they won't try to kill him. He really takes precautions against those people. He is able to summon and command some invincible relentless killers. And when you do meet him, he pretends to be some kindly wizard who will help you. In fact, you have to be pretty clever yourself to get him killed. 9/10
Globus really has it all covered. He already rules one world and from the point of view of most gamebooks, that's already game over. He has super powered killer servants (who are, however, not too bright) and makes sure that no one will kill him. It's only through a loophole that you have any chance of winning. 44/50