- "Even Seth knew that and he used to point at planes."
- ―William Herrick
Seth was a vampire henchman of Herrick's. Seth performed various duties for Herrick; including looking after Lauren when she was turned, as well as performing clean up services when a vampire kills their prey. He is generally considered to be quite slow by other vampires such as Herrick and Mitchell.
Seth was present at the time when Herrick turned Mitchell into a Vampire, while he and Mitchell knew each other they never really got on. Despite being older Seth seems intimidated by Mitchell; at times resorting to taunts in order to be seen as superior. Seth and his vampire friends Turlow and Marco beat up George two years ago when George and Mitchell first met. Seth is killed by Lauren with a stake through his heart in "Episode 1.5" when he is about to attack a cornered Mitchell, George and Annie in the vampire headquarters funeral home. He appears as an antagonist to George, as Herrick does to Mitchell, victimising him more than other vampires.
There are hints that Seth might be the Highgate Vampire.
Seth possessed all of the powers and abilities common to vampires; including immortality, advanced regeneration, invulnerability to most conventional forms of harm and fatality, awareness of the supernatural, enhanced strength, senses and resilience, and retractable fangs. Seth's image also could not be captured on film or in photographs, and his digestive system was modified to allow for the ingestion and digestion of blood. Due to his advanced age Seth should have been stronger than younger vampires; he was able to easily overpower the werewolf George Sands, however it should be noted that he was overpowered by the Vampire John Mitchell; a younger Vampire. Seth's enhanced senses allowed him to sense that George was a werewolf when they first met, and his enhanced resilience allowed him to endure having a chair smashed against his back and recover in moments; as though it was a mere annoyance. Seth's awareness of the supernatural allowed him to perceive the ghost Annie; it is hinted at during their encounter that it was the first time Seth had seen a ghost.