Asajj Ventress is a Dark Jedi from the planet Rattak, and one of Count Dooku's Force-attuned apprentices. She is a powerful warrior with exceptional combat abilities, and desires most of all to join the Sith order. She has many distinctive Sith tattoos and wields twin red lightsabers. She was under the tutelage of Ky Narec, however when Ky Narec was slain, she joined the dark side because she believed the Jedi abandoned Narec, and took up the ways of the Sith.
Each twelve marks on her head represent the twelve warlords she killed for revenge. She then became the dictator for Rattatak. (which the twelve warlords use to rule.) She was then discovered by Dooku in a gladiator arena. She was the last standing and he found her strong in the Dark Side of the Force. Later, she went with Durge to Ohama-D'un where she wiped out a Gungan colony with a swamp gas. They both knew Jedi would come, and when Obi-Wan came, they ambushed his team.
She finished off Glaive and Zule Xiss and almost killed Obi-Wan. Kenobi was saved by Skywalker and Alpha-17. Three months since the Battle of Geonosis, a plot was made between Asajj and the new member of the Separatists, the Jedi Sora Bulq. The plot was to eliminate some Jedi including Mace Windu. In a mock ambush, Asajj wounded Sora and killed Mira. The plot was going good until Mace Windu discovered the truth that Sora betrayed the Jedi Order. Mace Windu finished the duel with a Force Push into a rocky wall.
Before he could finish him off he sensed that his Jedi friends was in trouble and had to leave that very moment. Asajj almost killed K'kruhk and Sian Jeisel when Mace jumped on her back. After a few moments of lightsabers clashing, Asajj escaped in a solor sailor. Kenobi went after Ventress to save the lives of a few Jedi by getting the antidote from her. Asajj captured him but was forbidden to kill him as Dooku instructed. Obi-Wan escaped along with the antidote.
Asajj Ventress's home planet is Dathomir, later seen in The Courtship of Princess Leia. In the Clone War era, Ventress returns there to the Nightsisters where it was told she came from there but was taken at an early age. She seeks a male Zabrak to train and to be used as a spy against Count Dooku her now former Master. Savage Opress is empowered by Sith sorcery and later taught a crude usage of the Force by Count Dooku. She then attempts to defeat Dooku with Savage, but once again ends up betrayed this time by her agent.
Later, Dooku seeks vengeance on Ventress, Mother Talzin and the Nightsisters by sending General Grevious and the Confedarate troops to Dathomir. Ventress holds her own against Grevious, but the driod army overpowers and massacre the Nightsisters, with the exception of Ventress and Mother Talzin. Once again on her own, Ventress decided to resort to the life of a bounty hunter. Her exploits included teaming up with a young Boba Fett, saving Obi-Wan against Savage and his brother Darth Maul, and helping former Jedi Ashoka Tano.
One storyline told in the earlier Clone Wars comic series was the Obsession 4 part miniseries. This showed Obi-Wan Kenobi obsessed with hunting down and capturing Ventress. As Kenobi continued, it was Anakin Skywalker who played the role of mediator concerned that his Master was slipping close to the Dark Side with his fixation over Ventress. On Boz Pity, Ventress, wounded was attacked by both Kenobi and Skywalker. Once defeated and believed to be dying she was sent to Coruscant, however she was in a Jedi trance and directed the pilot to send her from the Jedis, Dooku and the war. Her whereabouts were unknown after this.