Who killed Anakin Skywalker?

in the end of Star Wars episode 6 nobody really kills Darth Vader/anakin skywalker but when he is throwing the emperor off the thing he gets shocked by his sith lightning and it keeps running trough his body because he is mostly made of metal so that's how he dies.

In a way Darth Vader actually kills Anakin in Revenge of the Sith when he turns to the Dark Side of the Force, as hinted at by Obi-Wan Kenobi in Return of the Jedi.
Anakin wasn't killed in the strictest definition. He redeemed himself when he saved his son Luke from being electrocuted to death by the Emperor, but doing so caused the lightning to compromise Vader's suit, which was pretty much a life support system. So Anakin's death was more of a sacrifice