Gainal'veruk, later known to the wider galaxy as Gain Alveruk - and to a select few as Darth Kardis - was a male Twi'lek who joined the Order of the Sith Lords during the dying centuries of the Galactic Republic, first as the apprentice of Darth Skiar and then as the reigning Dark Lord of the Sith and master to the Bith Darth Tenebrous. Kardis belonged to the Sith lineage begun by Darth Bane and Darth Zannah following the Seventh Battle of Ruusan almost a millennium earlier and adhered to Bane's Rule of Two, which restricted the Sith's numbers to one master and one apprentice at any given time.