The fantasy drama returns to US screens on Sunday, September 30 at 8/7c.
The 45-second clip features the resurgence of the evil Queen (Lana Parrilla) and also offers brief glimpses of new characters Sleeping Beauty (Sarah Bolger), Prince Phillip (Julian Morris), and Mulan (Jamie Chung).
The show's latest run will introduce a number of new fairy-tale characters, including Captain Hook (Colin O'Donoghue) and Sir Lancelot (Sinqua Walls).
Former Lost actor Jorge Garcia has also been cast in the new season as a giant.
In the UK, Channel 5 is expected to air the new season of Once Upon a Time in early 2013.
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