Watch: Star Wars Rebels Season 3 Thrawn Promo

For those who have not seen it, Star Wars Rebels, is set five years before A New Hope, chronicling the adventures of a rebel cell and their fight against the Empire. The main characters include Kanan Jarrus, a Jedi padawan veteran of the clone wars who was forced to into hiding, and Ezra Bridger, the first new Jedi trainee in an era where Jedi are hunted for extermination.

In the first two seasons, the heroes fight against the Inquisitors, dark force users trained by Darth Vader to hunt down Jedi who escaped the purge seen in Revenge of the Sith. After the rebels manage repeatedly to confound the efforts of the Inquisitors, Moff Tarkin decides to send in one of the best Imperial agents to destroy the nascent Rebellion once and for all.

Admiral Thrawn was a fan favorite of readers of the old Expanded Universe, which covered content outside of the films. The character featured as the main antagonist of his own series of novels, where he seized control of the fractured Empire to become a serious threat to the fledgling New Republic. When the old Expanded Universe was rendered non canon with the new sequel trilogy, fans feared Thrawn doomed to non canon. This is no longer the case, and viewers can look forward to Thrawn's second debut, this time in season 3 of Star Wars Rebels.