Dexter: Original Sin adds Sarah Michelle Gellar to the cast in a special guest starring role

A little over a year ago, Showtime announced that they were ordering a series – then known as Dexter: Origins, now known as Dexter: Original Sin – that would serve as a prequel series to their popular show Dexter, which finished its eight season initial run back in 2013, then recently came back for a new season (called Dexter: New Blood) that appeared to wrap things up for good… We’ve been hearing Dexter: Original Sin casting announcements here and there in recent weeks, and now Deadline has a new one: Buffy the Vampire Slayer star Sarah Michelle Gellar has been added to the cast in the special guest starring role of Tanya Martin, the CSI Chief at the Miami Metro Police Department and Dexter Morgan’s new boss.

Dexter: Original Sin follows Dexter in 1991 Miami, as a student transitioning into a serial killer in training. When his bloodthirsty urges can no longer be ignored, Dexter finds solace and understanding in Harry. As his only confidant, he teaches Dexter a Code that’s designed to help him find and kill people who deserve to die—all while avoiding getting caught by law enforcement. This is a particular challenge for young Dexter as he begins a forensics internship at the Miami Metro Police Department.

Played by Michael C. Hall in the nine seasons of Dexter, the title character is “a serial killer with a code which directs his compulsions to kill only the guilty. As a blood spatter analyst for the Miami police, he has access to crime scenes, picking up clues and checking DNA to confirm a target’s guilt before he kills them.“

Dexter: Original Sin will be available from Paramount+ with Showtime. The first season of the show is expected to consist of 10 episodes.

Gellar joins previously announced cast members Patrick Gibson of Shadow and Bone (as the young Dexter Morgan), Christian Slater of Mr. Robot (as Dexter’s dad, Harry Morgan), Molly Brown of Senior Year (as Dexter’s younger sister, Debra Morgan), Christina Milian of Falling Inn Love (as Maria LaGuerta, Miami Metro’s first female homicide detective), James Martinez of Love, Victor (as Angel Batista, an up-and-coming homicide detective who leads with his heart), Alex Shimizu of The Blacklist (as Vince Masuka, a forensic analyst who eagerly shares his expertise while relishing the chance to boss around his new intern, Dexter Morgan), Reno Wilson of Mike & Molly (as Bobby Watt, the longtime partner and confidant of Dexter’s adoptive father, Harry), and Patrick Dempsey of Grey’s Anatomy (Aaron Spencer, the Captain of Miami Metro Homicide who has a decades-long relationship with Harry Morgan).

Clyde Phillips, who served as showrunner on the first four seasons of Dexter and returned to the job for Dexter: New Blood, serves as showrunner on this new show as well. Phillips is also executive producing alongside Scott Reynolds, Mary Leah Sutton, Tony Hernandez, Lilly Burns, and Michael C. Hall. Robert Lloyd Lewis is producing with Showtime Studios and Counterpart Studios. Michael Lehmann, who directed Slater in the cult classic film Heathers, will serve as directing executive producer. The show is being creatively overseen by Gary Levine and Urooj Sharif for Showtime Studios, with production supervised by Tara Power. It will be distributed by Paramount Global Content Distribution outside of Paramount+ markets.

Last we heard, Dexter: New Blood is also expected to continue on Showtime, now shifting the focus to Dexter’s son Harrison. Phillips is overseeing the expansion of the Dexter franchise, with other possibilities in the line-up including “spinoffs that trace the back stories of some of the show’s most iconic characters. This includes John Lithgow’s memorable Trinity Killer.”

Are you interested in Dexter: Original Sin? What do you think of Sarah Michelle Gellar joining the cast? Let us know by leaving a comment below.