"Star Wars Rebels" season 4 premiered last week, with the two-part "Heroes of Mandalore" setting up the rebels' final battle against Grand Admiral Thrawn (voiced by Lars Mikkelsen) and the forces of the Galactic Empire. Thrawn has been the central villain since season 3, and he is going to serve the same purpose in the final one.

Executive producer Dave Filoni has confirmed this to The Daily News, saying, "He's still the one that is watching for them and that they're running from and their main competitor." However, the EP also revealed that Thrawn will not be the only threat in the animated series this time around.

Apparently, there is another antagonist hiding out there the somewhere that rebels may come across in the upcoming episodes. "There may some other villains more arch than him, hiding somewhere," Filoni teased further.

Filoni did not give away further details, only recommending that fans wait and see. However, Screen Rant says the most obvious candidate is none other than Darth Vader (James Earl Jones). The Sith Lord played an integral role in "Star Wars Rebels" season 2, going against ex-apprentice Ahsoka Tano (Ashley Eckstein) in the finale.

The ending left Ahsoka's fate as a bit of a mystery, as the character was last seen following an owl into the darkness just before the Sith temple collapsed on top of her. Now that the show is about to end, the show might bring back Vader again to give a clear answer on whether or not the former Jedi really died. Besides, the villain in question has "more arch" than Thrawn, according to Filoni. If there is any powerful antagonist who has a major spanning throughout the franchise, it would be the dark lord.

Then again, this is a mere speculation for now. But, there will hopefully be more details given as the series moves forward.

"Star Wars Rebels" continues next Monday, Oct. 30, at 9 p.m. EDT with episodes "The Occupation" and "Flight of the Defender" on Disney XD.