ZkinandBonez said: In the early drafts the name Vader actually referred to the Tarkin role (commander of the Death Star and not a sith) and a "Sith Knight" called Valorum played Vader's part, so his role is probably kind of hard to pinpoint in the pre-ESB canon of ANH.
In the rough/first draft, Tarkin is Crispin Hoedaack, Vader is a general, and Valorum is a Sith Knight. The second draft combined Vader and Valorum.