Onimi is a Shamed One — the lowest caste of Yuuzhan Vong society — who serves as familiar and jester to Supreme Overlord Shimrra Jamaane. He is introduced in Greg Keyes's Edge of Victory II: Rebirth (2001), disguised as the Master Shaper Kae Kwaad, and revealed at the close of the sequence as the invasion's true author: a botched shaping experiment that left him deformed, insane and Force-sensitive, in a species that had severed itself from the Force entirely.
It is the boldest swing the nineteen-book sequence takes, and readers have argued about it ever since. The complaint is that it converts a superbly alien civilisation into one madman's scheme; the defence is that a species which built its entire theology on the absence of the Force being led, unknowingly, by the one member who has it, is exactly the kind of irony the series had been building toward.
Catalogue entry. This figure has a verified record here rather than a full write-up — the encyclopedia labels its own depth instead of padding it.