Zaerith Menyar Ag-Gith, the so-called 'Great Githzerai' or the githzerai 'Wizard-King'. He's the spiritual leader of the githzerai, but officially has no political power, with that being the responsibility of a council of generals. In truth, he controls those secular rulers like puppets, exerting a massive, if indirect, amount of control over his race, and he can be pretty brutal against perceived rivals and threats to his power. He seems to genuinely want what's best for his race, and he feels that he's the best to guide them, so its only when you become a perceived threat to his own influence do you find yourself in trouble.
In 2e terms, IIRC he was a 20/20 wizard/fighter with the abilities of an Anarch (Xaos shaper). He was CN at the time as well, as I recall.
Unlike Vlaakith, he doesn't devour the souls of powerful githyanki, but potential rivals he generally exiles from Shrakatlor, the Floating City, and the other githzerai citadels. Additionally, those githyanki who venerate Zerthimon directly are forced into exile, living in monasteries apart from the rest of their people.
While some 3e sources might suggest otherwise, the hard-core monastary dwelling monk githzerai are outside the mainstream of their race, but as such given githzerai insular, quasi-xenophobic nature, these self-exiled 'zerai are the ones that non-githzerai are most likely to encounter and interact with.
And the githzerai choose Limbo because the chaos in many ways represents true freedom. Their constant struggle against it, seeking to shape it and control it by inner control and willpower, is a thing to prove their self-sufficiency, their will to never become slaves again, etc. They're not fighting the raw Xaos of limbo because they're lawful and trying to impose order on it, hardly, they fight it to prove their own absolute freedom from exterior forces.
