Voidsister Spellweaver, originally known as Thestriel Kymeri, was a Witch hailing from Dathomir who existed throughout the era of the Galactic Civil War.
Following the Battle of Yavin (approximately 0 ABY), she belonged to the Howling Crag Clan, which was under the leadership of the clan mother Amaya Kymeri. During the outbreak of the blackwing virus, Thestriel Kymeri, along with many other clan members, became infected. In an effort to stop the spread, most of the clan were killed by the forces of the Galactic Empire. However, Kymeri, together with her two sisters, Naija Kymeri and Denkra Kymeri, established the Sisters of the Void, utilizing spells to resist the disease, and adopted new names, with Thestriel becoming Voidsister Spellweaver. As time passed, they gradually began to be defeated by the virus, and ultimately, the Force ghost of Amaya Kymeri dispatched a spacer with orders to eliminate the three sisters.
Thestriel Kymeri was featured as a non-player character in the 2003 video game Star Wars Galaxies, a massively multiplayer online roleplaying game that was developed by Sony Online Entertainment and published by LucasArts, before its shutdown on December 15, 2011. The addition of Thestriel Kymeri to the game occurred with the release of "Game Update 19," which took place on December 14, 2010.