The casting was announced Saturday morning during the upcoming series' Comic-Con panel, with the actor making a surprise appearance.

SAN DIEGO — A Lost alum is heading to Wonderland.

Naveen Andrews, best known for playing Sayid for six seasons on the ABC drama, has joined the cast of the Once Upon a Time offshoot, Once Upon a Time in Wonderland, it was announced Saturday morning during its Comic-Con panel.

Who will Andrews play? The villainous Jafar, a character that was featured as the main antagonist in the 1992 animated Disney classic Aladdin. This iteration of the character will be "radically different," Andrews told the crowd. He will first appear in the premiere episode.

PHOTOS: The Scene at Comic-Con 2013

The casting of Andrews in the anticipated Wonderland series is a coup for ABC, which had previously cast the English actor in one of its drama pilots, Reckless, that failed to get a series greenlight. The news marks a reunion of sorts for the Gersh-repped Andrews, who worked with Wonderland executive producers Edward Kitsis and Adam Horowitz on Lost.

Since Lost, Andrews starred in Syfy's Sinbad drama and next co-stars in Diana, the Princess Diana feature opposite Naomi Watts.

Andrews made a surprise appearance during the Wonderland panel in Ballroom 20 to rapturous applause and screams.

Prior to the casting announcement, the 20-minute presentation was screened for the very first time in front of a public audience.

The producers assured the crowd that while Once follows a more open-ended story, Wonderland will close out the mystery at the end of the first season. Questions that will be answered this season include Alice's back story with all the characters, why Jafar is in Wonderland and how the genie got into the bottle. "We intend to be all killer, no filler," Kitsis said, adding: "There will be flashbacks in every episode ... just like Once."

Roger Daltrey will continue to voice the caterpillar, the producers revealed, while the Cheshire cat will be seen at some point this season, as well as the possibility of a Queen of Hearts sighting.

Horowitz revealed that he and Kitsis had been approached during the first season of Once to create a possible spinoff, the duo opted to wait because they had no ideas to expand upon.

Wonderland takes place in Victorian England, where the young and beautiful Alice (Sophie Lowe) tells a tale of a strange new land that exists on the other side of a rabbit hole. The cast includes Michael Socha as Knave of Hearts, Peter Gadiot as Cyrus, Emma Rigby as Queen of Hearts and John Lithgow as the voice of the White Rabbit.

Steve Pearlman and Zack Estrin join Kitsis and Horowitz as executive producers, with the pilot directed by Ralph Hemecker.

Once Upon a Time in Wonderland premieres Oct. 10 at 8 p.m. on ABC.

E-mail: Philiana.Ng@THR.com

Twitter: @insidethetube