Expanded Universe: Dark Lord, The Rise of Darth Vader - R4-K5, Darth Vader's Astromech Droid. When Anakin Skywalker falls to the dark side and becomes Darth Vader, he casts off his entire past. To further embrace this change, he paints his starfighter black and chooses a black astromech droid to replace his former droid companion R2-D2. The outer darkness of his fighter and droid mirrors the inner darkness of the new Sith Lord.