Stephen Hawking is one the most celebrated - and popularly recognised - physicists alive today. He also has a claim to being one of the most influential physicists to have ever lived.
Hawking's works focuses primarily on cosmology and quantum gravity. He became famous outside of academia on the publication of A Brief History of Time in 1988. The book deals with cosmology, especially black holes and the Big Bang, and has sold over 9 million copies. When a publisher told Hawking that for each equation printed his readership would halve he removed all but one (e=mc2), replacing them with illustrations to communicate the concepts in his book to a wider public.
Despite these efforts, A Brief History of Time is one of the books most commonly left unfinished by readers.