Antagonist

Character Role Analysis

Darth Vader and Grand Moff Tarkin

Assuming you aren't rooting for Darth Vader, then it becomes obvious that he and Grand Moff Tarkin fit comfortably into the role of antagonists. They want to retrieve the Death Star plans and hunt down those wascally webels.

Luke wants to save princess Leia and bring the Death Star plans to the Rebels. That sounds like the makings of a conflict for us, and if you're in conflict with the protagonist, then you're the antagonist. That means it's wascally webel season.