Sev'rance Tann was a Chiss female who left Chiss Space to become a Dark Acolyte and general in the Separatist Droid Army during the First War. Hailing from Csilla in the Unknown Regions, she became one of few Chiss to leave her people during her time, along with her lover Vandalor, both becoming agents of Count Dooku and the Axis of Empires shortly before the outbreak of the War. Dooku taught Tann the use of the dark side of the Force, and she became one of his most trusted underlings. When the war broke out, Tann fought at Yetsan IV and later commandeered the Archangel Orbital Platform for Axis use. When Dooku learned of the new Republic technology known as the Decimator, Tann was ordered to locate the weapons and steal them for the CIS to use.