Shimrra Jamaane is the Supreme Overlord of the Yuuzhan Vong, the absolute religious and political authority of the invasion. He is referred to well before he is seen; he appears on the page in Greg Keyes's Edge of Victory II: Rebirth (Del Rey, 2001), and thereafter through villip communication and in person as the series closes in on the conquered Coruscant.
He is written as terror in its purest institutional form: enormous, ancient, unquestionable, and holding a court in which every other character's survival depends on the accuracy of their flattery. The Warmaster Tsavong Lah is frightened of him. So is Nom Anor, who is frightened of very little.
The reveal at the end of the sequence is that the terror was borrowed. Shimrra's Shamed jester, Onimi, has been steering him for decades — the Supreme Overlord is a mouth, and the thing behind him is a deformed court fool with a Force ability no Yuuzhan Vong is supposed to possess. Luke Skywalker kills Shimrra in The Unifying Force (2003) and only then discovers he has killed the wrong one.
