Meet The Resistance
Oscar Isaac as Poe Dameron: One of a few characters crossing over from the big screen to the little, Poe Dameron appears in the first episode of Star Wars Resistance. He's working to uncover any information he can about rumors the First Order is planning a direct attack against the New Republic, recruiting Kaz to be his eyes and ears on Colossus. Since the series is set just six months prior to the events of The Force Awakens (wherein that rumored attack becomes a reality), Poe is largely the same confident, dashing pilot we first meet at the start of Episode VII. Oscar Isaac returns to voice Poe, who will presumably appear sporadically throughout the series.
Rachel Butera as General Leia Organa: Given the timeframe of the series, the Resistance is still in its early stages and General Leia Organa is hard at work building the coalition. Leia only appears briefly in the first episode of Star Wars Resistance, glimpsed conferring with Poe via holovid. She is voiced by actress/impressionist, Rachel Butera, who has several voice credits across many series, including recent iterations of Teenage Mutant Ninja Turtles and The Adventures of Rocky and Bullwinkle.
BB-8 as BB-8: When Poe leaves Kaz to his spy duties on the Colossus, he leaves behind his trusty droid, BB-8 to watch over him. BB-8 is the only movie-character who will regularly appear on Star Wars Resistance.
Meet The First Order
Lex Lang as Major Vonreg: Though only seen in the opening minutes of the Star Wars Resistance premiere (and again, briefly, in the final minutes), Major Elrik Vonreg is poised to be the main antagonist of the series. A pilot in the First Order, Vonreg flies a modified TIE Fighter and wears a custom TIE pilot uniform - both in a very distinct crimson shade. Dave Filoni considers Vonreg to be their version of the Red Baron. He's voiced by actor Lex Lang, who has credits across dozens of anime and cartoons, even including a stint as Poe Dameron in LEGO Star Wars: The Resistance Rises.
Gwendoline Christie as Captain Phasma: At this point in the timeline, Captain Phasma is training the next generation of stormtroopers (including one FN-2187 - AKA Finn) and hunting down Resistance spies - a task that will bring her directly into the action of this series. Phasma is expected to first appear in episode three, 'The Triple Dark', where actress Gwendoline Christie will reprise her role from the films as the chrome-clad commander.
Adam Driver as Kylo Ren: As of this writing, Kylo Ren appearing on Star Wars Resistance hasn't been officially confirmed, but a ship that looks very similar to Ren's command shuttle can be spotted in the extended trailer. Plus, given the time frame, it'd make a lot of narrative sense to work the character in, not too mention possibly including the Knights of Ren or even General Hux. Were Kylo Ren to appear, it's likely Adam Driver would reprise the role similarly to what his film co-stars have done.
Star Wars Resistance premieres this Sunday, October 7th at 10pm/9c on the Disney Channel, with subsequent episodes airing on Disney XD.