Stephen William Hawking, CH, CBE, FRS, FRSA (born 8 January 1942) is a British theoretical physicist. Hawking is the Lucasian Professor of Mathematics at the University of Cambridge (but intends to retire from this post in 2009), a Fellow of Gonville and Caius College, Cambridge and the distinguished research chair at Waterloo's Perimeter Institute for Theoretical Physics. He is known for his contributions to the fields of cosmology and quantum gravity, especially in the context of black holes. He has also achieved success with works of popular science in which he discusses his own theories and cosmology in general; these include the runaway best seller A Brief History of Time, which stayed on the British Sunday Times bestsellers list for a record-breaking 237 weeks. Hawking has a neuro muscular dystrophy that is related to amyotrophic lateral sclerosis (ALS), a condition that has progressed over the years and has left him almost completely paralysed.

Hawking's key scientific works to date have included providing, with Roger Penrose, theorems regarding singularities in the framework of general relativity, and the theoretical prediction that black holes should emit radiation, which is today known as Hawking radiation (or sometimes as Bekenstein-Hawking radiation). He is a world-renowned theoretical physicist whose scientific career spans over 40 years. His books and public appearances have made him an academic celebrity. He is an Honorary Fellow of the Royal Society of Arts, and a lifetime member of the Pontifical Academy of Science.

Stephen Hawking was born to Dr. Frank Hawking, a research biologist, and Isobel Hawking, a political activist. He had two younger sisters, Philippa and Mary and an adopted brother, Edward. Though Hawking's parents were living in North London, they moved to Oxford while Isobel was pregnant with Stephen, desiring a safer location for the birth of their first child (London was under attack at the time by the Luftwaffe). According to one of Hawking's publications, a German Wehrmacht V-2 missile struck only a few streets away.