Dr. John T. Foster is a character in the TV series Skins, who appears as a minor antagonist in the fourth season, more specifically in episodes "Effy" and "Everyone". He is played by a British actor Hugo Speer.
Dr. Foster is a psychiatrist who attempts to rehabilitate Effy after her suicide attempt. He eventually develops an obsessional crush on Effy and tries to make her fall for him any means necessary. Foster steadily makes Effy's mental issues worse in order to rebuild her for his own image, alienating her from her mother and Freddie in the process.
Freddie eventually finds out about Foster's secret and as a result, Foster murders him with a baseball bat. Cook later finds Freddie's bloody clothes in his basement and is ambushed by Foster. Foster reveals his intentions with Effy and tries to murder Cook as well. However, enraged for what he did to Freddie and Effy, Cook manages to fight back and kill Foster for revenge and as a result, Cook becomes a fugitive.