Darth Vethra

"The hate that created Darth Vethra is a powerful one. Such unkempt hatred is fuel to the Dark Side, and Vethra revels in it. It consumes her. In truth, she is more powerful than her master."

Darth Vethra was a Dark Lord of the Korribanite Empire of the first  Korriban Triumvirate during the Relic Wars. The result of a genetic experiment on Sith purebloods, Vethra escaped from the Rosolon Facility on Korriban and became rogue, before she was recruited by Darth Exius and trained as his apprentice.

Following the death of Darth Rehmmus, and the creation of the first Korriban Triumvirate, Vethra became a Dark Lady of the Sith, and grew in strength.