In an interview with Entertainment Weekly, Lucasfilm president, Kathleen Kennedy was asked which characters from the original Star Wars trilogy might give an appearance in Rogue One: A Star Wars Story. She confirmed not only would Darth Vader be involved in some capacity, but James Earl Jones would be back to provide his voice!
Kennedy went on to say Vader will be sparingly used, but "at a key, strategic moment, he's going to loom large." It was also revealed that Vader and main Rogue One big bad, Director Orson Krennic will hate each other.
Rogue One: A Star Wars Story will be in theaters December 16, 2016.