Patient One
From Tardis Wiki, the free Doctor Who reference
Patient One was a patient at Hawthorne. His existence there was apparently secret. After Patient Zero's death and the thwarting of Dr Colin Dove's plan at perihelion, Peter Russell had a strange reaction to holding a knife and seemed to have a connection to Patient One, who laughed menacingly and sang "Daisy Bell" just as Zero and Russell had whilst possessed by the reservoir of evil. (HOMEVID: The Zero Imperative)
Behind the scenes
Patient One was played by Peter Davison.
