'Eureka,' 'Sanctuary' announce guest stars

Felicia Day plans 'Eureka,' Polly Walker to visit 'Sanctuary'

Syfy announced two guest stars for its returning series that had fans buzzing at Comic-Con.

Felicia Day, of the Web series "The Guild" and "Legend of Neil," as well as "Dr. Horrible's Sing-Along Blog," joined the "Eureka" panel Saturday to announce that she'll be appearing in 10 episodes of the show.

In addition, Syfy announced that Polly Walker will guest star on Syfy's "Sanctuary" for two episodes next season.

Walker, who is best known for HBO's "Rome" and Syfy's "Caprica," will play Ranna, a powerful foe who faces Helen Magnus (Amanda Tapping) after the team encounters her in the show's mid-season cliffhanger. A Syfy rep confirmed the role won't impact her "Caprica" duties.