Whether you remember or not, Anakin Skywalker becomes Darth Vader before losing his body in Revenge of the Sith.

Darth Vader's true identity as Anakin Skywalker was a highly guarded secret, known only to a select few individuals including Palpatine, Obi-Wan Kenobi, Luke, Han, Leia, R2-D2, C-3PO, Master Yoda ...