The Supreme Overlord functioned as the monarch for the Yuuzhan Vong people.
Acting as a god-king in essence, the Supreme Overlord served as the connection between the Yuuzhan Vong and their deities, possessing exclusive communication rights with Yun-Yuuzhan. Successorship did not follow hereditary lines; instead, prospective Overlords were selected from a group of individuals whose births were marked by significant omens, prophetic signs, and distinguished ancestry. Twin births were exceptionally uncommon amongst the Yuuzhan Vong; when they occurred, the twins engaged in a fight to the death at the age of seven, with the survivor eventually ascending to the position of Supreme Overlord.
Each candidate received comprehensive training in all facets of Yuuzhan Vong society, treated with the respect and preparation befitting a designated heir. The Supreme Overlord often gained their position by assassinating the current Overlord. Overlords donned ceremonial garments crafted from the skinned and preserved remains of Steng, the inaugural Warmaster, and Yo'gand, the first Supreme Overlord, figures who clashed in the Cremlevian War that unified the Yuuzhan Vong. Upon their ascension, the Supreme Overlord underwent ritualistic scarring and physical alterations, sacrificing various external organs and limbs to emulate the appearance of Yun-Yuuzhan.
In terms of political structure, the Overlord wielded authority and power encompassing the Intendant caste and Warrior caste, also serving as the paramount religious figure (Priest caste), thereby holding a rank superior to the High Prefect, Warmaster, and High Priest.
Shimrra Jamaane was widely believed to be the last Supreme Overlord—he initiated the invasion of the galaxy a millennium after the Yuuzhan Vong abandoned their devastated primordial homeworld in search of a new place to live. However, it was revealed that Shimrra was merely a figurehead, manipulated by the true power, Onimi. The real Supreme Overlord met his end at the hands of Jacen Solo within Onimi's escape pod above Coruscant. Following the deaths of Onimi and Shimrra, the Yuuzhan Vong found themselves without a Supreme Overlord for the first time in their recorded history.