Onimi

Onimi was a male Yuuzhan Vong who was born into the Shaper caste and who, through experimentation, accidentally restored his own Force sensitivity, something that had been lost to his ancestral species for thousands of years. His body physically twisted by his experiments, Onimi was branded a Shamed One and blamed the Yuuzhan Vong gods for his misfortune, but kept his newfound Force powers a secret and used them to maneuver himself into the position of court jester for Supreme Overlord Shimrra Jamaane—a position he used to mentally dominate the Overlord.

Effectively the shadow ruler of the entire Yuuzhan Vong empire, Onimi masterminded his species' invasion of the galaxy, and disguised himself as Kae Kwaad to work with the heretical Shaper Nen Yim to fill out the empty eighth cortex of Yuuzhan Vong shaping knowledge. However, the Galactic Alliance began to make progress against the Yuuzhan Vong and ultimately sought to reclaim their capital, and Onimi's control over Shimmra began to slip as the war reached its final stages and his own sanity further crumbled. In 29 ABY, after Shimmra was slain during the Battle of Yuuzhan'tar, Onimi faced the Jedi twins Jaina and Jacen Solo and revealed himself and his powers, believing them to be the gods Yun-Harla and Yun-Shuno. Onimi attempted to use the Alpha Red pathogen to kill the living world Zonama Sekot in a crazed attempt to make himself into a god, but his plan was foiled when Jacen became one with the Force and obliterated the twisted Shaper, dissolving him into atoms and ending the Yuuzhan Vong War.

Text and facts from the “Onimi” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.