Once known as Anakin Skywalker, he was turned to the Dark Side of the Force. When Obi-Wan Kenobi tried one final time to turn him back, they battled. During the dual, Anakin was knocked into a pit of molten lava. He emerged as nothing more than an empty human body. He was
barely alive. Thus, a
big, scary black suit was made that forced him to breathe and took care of his body. Later, he and his son,
Luke Skywalkar fought. Near the end of the battle, Luke, in a fit of rage, cut off
Vader's right hand and destroyed the control panel on the big black suit. Darth Vader, doomed to die, watched his son being tortured by Emperor Palpatine. Finally, he came to his senses. Emperor Palpatine was hoisted with one hand and launched into the Death Star's reactor core. Anakin Skywalker was reborn in that moment, and he died trusting the good side of the Force. Now an apparition, he watches Luke from afar through all of his adventures.
Example:
"The ability to blow up a planet is insignificant next to the power of the Force."
"Impressive. Most impressive."
"You are beaten."
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Darth Vader
"Luke... You were right about me... Tell your sister... you were right..."
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Anakin Skywalker's last words