Want to learn more about Bob, the "air spirit" who lives in a skull on "The Dresden Files"? Then tune in to the SciFi Channel on Sunday, April 1, for "What About Bob?"

"As you know, Bob is an apparition," said Terrence Mann, the Tony Award-nominated actor who brings Harry Dresden's assistant to life on the show. "He only exists in ghost form. But in this particular episode, some things happen that allow him to transform. And you'll have to watch to see what he transforms into."

While playing a disembodied spirit may seem far out to some, Mann's acting resume has helped him prepare for the role, Mann told SciFi Wire.

"I liken it to playing Shakespeare or any sort of great, fantastical character," Mann said. "I played a cat in 'Cats.' I played Beast in 'Beauty and the Beast' and Javert in 'Les Miserables.' And all of those characters are sort of fantastical in nature. So I feel right at home doing the Bob thing."

"The Dresden Files" airs Sundays at 9 p.m. ET on the SciFi Channel.