Skere Kaan

Skere Kaan was a male Human Jedi Master who served the Jedi Order in the last years of the New Sith Wars before defecting to become a Dark Lord of the Sith and creating the Brotherhood of Darkness within the reorganized Sith Empire, earning him the nickname of the "Dark One". Ruling the Sith for a decade, Kaan's reign was turbulent as the Brotherhood was rife with civil unrest, and conflict with the Jedi saw his numbers dwindle. A few Sith were starting to question his beliefs, including Darth Bane.
At the end of the bloody Ruusan campaign, Kaan, his followers, and much of the Jedi Army of Light were destroyed by a thought bomb of his own creation during the Seventh Battle of Ruusan. In Kaan's place, Darth Bane, who tricked the entire Brotherhood into its destruction, set up a new Sith order with the Rule of Two: one master and one apprentice.