Stephen Hawking was a human scientist and theoretical physicist in the late 20th early 21st century.
In 2004, Hawking attended the opening of the Tomorrow Windows at Tate Modern. (EDA: The Tomorrow Windows)
When Dalek Thay encountered the Cybermen, Mickey Smith compared this to Stephen Hawking meeting the speaking clock, a reference to his paralysis which required him to use a voicebox to speak. (DW: Doomsday)
Stephen Hawking died some time before 2050, where the famous scientist Alistair Gryffen used the phrase "Hawking's Ghost!" to express shock. (K9TV: The Last Oak Tree)
