|Occupation||psychic working under Kemp|
|First appearance||Cure and Contagion|
|Last appearance||All God's Children|
Hennessey is a psychic working under Kemp in Series 2. He is first seen around the end of Episode 2.1 as a convict going along with Kemp to test any supernatural presence in the flat. He later acts as a medium between Annie and Kemp in the initial attempt to allow Annie to pass on which was interrupted by one of George's oncoming transformations. He resides in Kemp's facility following Annie moving there and shares a room with her, apparently befriending by her. When Kemp tries to forcibly exorcise Annie, Hennessey stands up for her and points out the lack of the Door, causing Kemp to kill him for one. After seeing his own dead body on the floor and Annie for the first time, his Door appears and they are both forcefully dragged in.
Hennessey displayed far greater control over his ability than other psychics. Aside from hearing ghosts, he was able to sense the residue of Annie's presence in her home (and distinguishing it from her actually being present at the time) and he had shown that he could determine her exact location by focusing his ability.