Holy crap. Rebels has a new Big Bad, and it’s an old Big Bad—Grand Admiral Thrawn, the brilliant Imperial military commander who took over the remnants of the Empire in the old Expanded Universe, as revealed in the very first EU novel trilogy by Timothy Zahn.
Some things to note: 1) He’s definitely referred to as “Grand Admiral.” 2) There’s no mention of anything else from Heir to the Empire or the other two books of the trilogy, so don’t go think those novels have suddenly been added wholesale to the new canon. 3) He’s being voiced by Lars Mikkelsen, brother of Rogue One star Mads. 3) Timothy Zahn sent a video message giving his full approval. Nice!
Update: Zahn is writing a new Star Wars novel titled—wait for it—Thrawn, due 2017. This isn’t just a cameo, guys.