She believed that, due to her relationship with Padalecki, the production staff were waiting until the "perfect role" arrived before casting her.[21] The role of the immortal Doc Benton was reserved for actor Billy Drago, whom executive producer Kim Manners had previously worked with on the television series The Adventures of Brisco County, Jr.. A fan of Frankenstein-actor Boris Karloff, Drago said of the role, "This was an opportunity to play both Dr. Frankenstein and his creation simultaneously. Instead of creating some immortal monster, he makes himself immortal.