Sincodemiaas

Sincodemiaas was a Human Jedi who turned Sith after the Clone Wars and was ultimately killed by the Emperor.

History
Sincodemiaas began life as a simple Jedi, who was, like most of the Order, devastated by the outbreak of the Clone Wars. In the beginning months he was sent, along with eleven other Jedi padawans, to a Tatooinian city called Mos Osnick, just south of its sister town, Mos Osnoe. The Jedi Council only sent padawans because they truly did not believe Tatooine would be attacked; however, they were wrong. The CIS, now refitted with Strike Mechs and Mech Destroyers, raided the town. Sev'Rance Tann, the pre-Grievous General of the CIS, cut down most of the padawans. Sincodemiaas' left army was severed and she cut out a portion of his torso and his right leg with her lightsaber. Using the Force to survive, Tann ordered her droids to kill the "persistent" Jedi while she took on other matters, and a portion of Sincodemiaas' head was destroyed by gunfire. Most of his memory was wiped when the memory portion of his brain was injured. Apparently, the otherwise unimportant Jedi was dead...or so it seemed.

Somehow, Sincodemiaas clung to life in the ruins of Mos Osnick up until 0 ABY. He was left in a trance, but was awakened by the sound of gunfire; none other than that of Tantive IV, the ship Princess Leia Organa was on. Having no idea who he was, he came across a damaged Protocol Droid, which was destroyed in the fighting. The droid, who was actually one of the Jedi padawans, telepathically called out to him. The droid then made a queer request: use pieces of his body to rebuild the damaged portions of Sincodemiaas' own body. Thanks to the droid, Sincodemiaas managed to survive the ravages of his body and later used the droid to build armor over his own body. It is unknown what happened to the two Jedi over the years (as the droid Jedi's personality was in Sincodemiaas' brain due to the merger), but eventually the recently resurrected Sev'Rance Tann. Although outraged at the return of his killer, the rage turned to gratitude when the shock restored his memories. Obviously, the years had taken a toll on Sincodemiaas' mind, and he no longer had control over his emotions.

In a very disturbed state, Sincodemiaas telepathically destroyed the consciousness of the droid jedi and agreed to be Sev'Rance sith apprentice. He then joined in her plot to kill Vader and the Emperor. After months of planning, the two Sith attacked the incomplete second Death Star and attacked the Emperor and the one who was once Anakin Skywalker. Sev'Rance was killed by Vader, unknown to Sincodemiaas, who had taken on the Emperor. The didn't last long--neither drew their lightsabers. The Emperor struck down Sincodemiaas by using Force lightning to short circuit the Sith's armor, causing it to explode. Sincodemiaas, burned beyond repair by the explosion, stumbled into the shaft that eventually would kill the Emperor himself. The energy there caused his body to explode, killing him instantly.