Sarah Michelle Gellar has joined the cast of 'Dexter: Original Sin', a project that appears to be related to the existing 'Dexter' series, possibly a prequel. The show's existence suggests that the 'Dexter' series may have been revived or reimagined in some way, despite reports of a previous cancellation. Details about the show, including its season count, are emerging, with the series set to be featured at San Diego Comic-Con.