Patrick Dempsey to join Dexter: Original Sin prequel series as a main cast member

Patrick Dempsey is fleshing out the cast of the upcoming serial killer series Dexter: Original Sin.

The 58-year-old Grey's Anatomy star is joining the prequel series as a main cast member, according to Variety.

The upcoming show explores the early days of the psychopathic serial killer Dexter Morgan, with Patrick Gibson, 29, playing a young version of the killer-turned-forensics expert.

The new gig comes after Dempsey earned stellar reviews in Michael Mann's Ferrari as the racing driver Piero Taruffi.

On Dexter: Original Sin, the film and television star is likely to have a complicated relationship with the title character.

Dempsey will be playing Captain Aaron Spencer of the Miami Metro Homicide department.

The character is a friend of Harry Morgan, Dexter's father and a fellow officer in the police department.

'Patrick Dempsey is a beloved actor who is internationally known for the iconic characters he has played and his performances,' Paramount Global co-CEO Chris McCarthy said. 'We are thrilled to have him join our all-star cast of Dexter: Original Sin, the highly anticipated origin story of the franchise.'

Christian Slater will be taking over the younger version of Harry from James Remar, who played the character in extensive flashbacks throughout the original series.

Dexter's father was the first person to recognize his psychopathy and homicidal desires, which he channeled into teaching Dexter to murder other killers.

When he wasn't tracking down killers to sate his bloodlust, Dexter was an accomplished blood-splatter analyst for the Miami PD.

The new series begins in 1991, 15 years prior to the start of the original Dexter series. 

According to the official synopsis, Original Sin follows young Dexter as he 'transitions from student to avenging serial killer.'

'When his bloodthirsty urges can’t be ignored any longer, Dexter must learn to channel his inner darkness. With the guidance of his father, Harry (Slater), he adopts a Code designed to help him find and kill people who deserve to be eliminated from society without getting on law enforcements’ radar,' the synopsis reads. 'This is a particular challenge for young Dexter as he begins a forensics internship at the Miami Metro Police Department.'

The original hit series aired from 2006–2013, and Showtime revived it for Dexter: New Blood in 2021. 

In addition to Dempsey, Gibson and Slater, Dexter: Original Sin will star Molly Brown as Dexter adopted sister Debra Morgan, James Martinez as Angel Batista (originally played by David Zayas), Christina Milian as Maria LaGuerta (previously played by Lauren Vélez), Alex Shimizu as Vince Masuka (originated by C. S. Lee) and Reno Wilson as Bobby Watt.

The series will also feature the return of Clyde Phillips as showrunner and executive producer, the same roles he performed on the original series.

Although original star Michael C. Hall doesn't appear to be featured in the series, he is returning as an executive producer, along with Scott Reynolds, Mary Leah Sutton, Tony Hernandez and Lilly Burns.

Dempsey has a string of popular films and TV shows under his belt, but he's best known for playing Derek 'McDreamy' Shepherd on Grey's Anatomy.

People's Sexiest Man Alive (2023) also established himself as a leading man in romantic comedy films, including Enchanted, Sweet Home Alabama and Maid Of Honor.