The ABC drama stars Jennifer Morrison as Emma, a young woman with a troubled past who moves to a small town where the magic of fairytales appears to be real.
Lost star Dale will play the father of Prince Charming (Josh Dallas), according to TV Line.
"It's a really pivotal role, and a pivotal part of the Snow White (Ginnifer Goodwin) and Prince Charming story that we don't think has been told yet," said producer Adam Horowitz.
Dale is initially booked for just one episode, though Horowitz hinted that he could reappear later in the first season.
"We're leaving the door open for a larger tale to potentially tell with him," he explained.
The actor has previously appeared in episodes of 24, Ugly Betty, The OC and Torchwood.
Other stars confirmed to appear in the show include Buffy actor Harry Groener, Breaking Bad's Giancarlo Esposito and Falling Skies star Jessy Schram.
Once Upon a Time premieres on Sunday, Oct. 23 at 8/7c.
> Once Upon a Time to 'explore fairy-tale mysteries'
Watch Ginnifer Goodwin and Josh Dallas discuss Once Upon a Time with Digital Spy below: