Asajj Ventress was a character in the Star Wars animated series, The Clone Wars. Her story received closure in the fifth season of the show, where she played a role in helping clear Ahsoka Tano of serious crimes against both the Republic and the Jedi Order. After that, she disappeared from the world of the Star Wars animated series and was not mentioned in seasons 6 and 7. However, a 2015 novel called Dark Disciple, which was based on unused stories from The Clone Wars, provided some sort of closure to her story.
Asajj Ventress was an assassin trained in the ways of the dark side by Count Dooku, and she fought with twin red-bladed lightsabers. After Dooku rejected her as his apprentice and tried to kill her, Ventress returned to her roots as a Nightsister, made a living as a bounty hunter, and rediscovered the way of the light that she had rejected long ago as a Jedi Padawan. Her life took many sad turns, leading her from light to dark and places in-between.
There is a non-canon comic book called Star Wars: Obsession where Asajj Ventress dies in Obi-Wans arms. However, this is not considered part of the official Star Wars canon.