Barriss Offee

"I did it. Because I've come to realize what many people in the Republic have come to realize, that the Jedi are the ones responsible for this War. That we've so lost our way that we have become villains in this conflict, that we are the ones that should be put on trial, all of us! And my attack on the Temple was an attack on what the Jedi have become: an army fighting for the Dark side, fallen from the Light that we once held so dear. This Republic is failing! It's only a matter of time."

- Barsiss' confession

Barriss Offee is the hidden main antagonist in the last four episodes (and consequently the final antagonist) in the fifth season of the TV show Star Wars: The Clone Wars. She is a Mirialan Jedi Knight, General and Healer. She carries a blue lightsaber (later two red lightsabers) and was a friend to Ahsoka Tano, as well as a mentionable character in Season One and a secondary character/supporting protagonist in Seasons Two, Three and Four before becoming one of the main antagonists in Season Five.

History
Barriss was once the loyal Jedi Padawan of Luminara Unduli and skilled healer. In the period of the Clone Wars, she earned the rank of Jedi Knight and General. However, as she was fighting in this galactic conflict, she slowly realized how bad it is. She believed (correctly) that the Jedis became too corrupted and had always been the true ones responsible for the Clone Wars, that the Jedi are the real villains, the real ones to be put on trial. This led her to secretly fall to the Dark Side.

To show her protest, she launched a secret bombing on the Jedi Temple. She forced Letta Turmond to feed explosive nano-droids to her husband, Jackar Bowmani, who worked in the Jedi Temple as a munitions expert. Next day in the hanger, nano-droids blew up, killing Jackar and six Jedi as well as clone troopers. All evidence led to Letta and she is sent to the prison. When Ashoka came to see her, Letta was Force-choked to death by Barriss, but it was Ashoka who ended up in the prison for "killing" her.

Barriss later entered the prison, killed several guards and helped Ashoka to escape, with her believing it was her master, Anakin Skywalker, who helped her. Unfortunately, Ashoka was blamed of killing the guards and had to flee and attempt to prove her innocent. She contacted Barriss who pretended to help her and led Tano to a warehouse. She then knocked off Asajj Ventress, stole her mask and lightsabers and attacked Ashoka, disguised as Ventress. Their duel ended when Tano fell off a balcony, landed near crates of nano-droids and was found by the clones.

Meanwhile, Anakin, who believed Ahsoka innocent, hunted down proof for the real killer. He questioned Ventress who told him that Ashoka was in contact with Barriss. He came to Barriss' quarters where she attacked him with Ventress' lightsabers. He eventually managed to capture her.

Anakin brought Barriss to Ashoka's trial, saving her Padawan from the capital punishment. Barriss told the truth to the court. She stated she felt that the Jedi were corrupted and guilty from the Clone Wars. Afterwards, she was imprisoned and all charges against Ahsoka were dropped.