Originally posted by T.M
two people played him. David Prowse played the actual character and James Earl Jones done the voice.i think that is the right way round anyway.
except for the end of ROTJ when he was dying and when he was a ghost he was played by Sebastian Shaw
also in ROTJ Prowse's stunt double (Bob Anderson) played Vader through parts of the film... (due to a falling out between Lucas and Prowse)
and if you want a FULL, full answer.... then you may have to include the newly added part at the end of ROTJ where Hayden Christensen plays Ghosty Vader