(written from a Production point of view)
Stephen Hawking (8 January 1942 – 14 March 2018; age 76) was a noted scientist who formerly held the Lucasian Chair at Cambridge University in England. Diagnosed at age 22 with Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease), he used a wheelchair for the majority of his life, and communicated by means of an electronic vocal synthesizer. He was famous for formulating several theories regarding the nature of black holes, often working with colleague Kip Thorne, and for his best-selling science books including A Brief History of Time.
Hawking is the only person, to date, to have played himself on Star Trek (excluding historical people who have appeared via stock footage), appearing as his own holographic counterpart in the Star Trek: The Next Generation sixth season episode "Descent" in 1993. While filming the episode, Hawking was taken on a tour of the engineering set; indicating the warp core, he said, "I'm working on that." (Star Trek Encyclopedia (3rd ed., p. 185)) On a subsequent visit to the set, he passed by actor Brent Spiner and asked where his money was from winning the hand of poker. Spiner replied that the check was in the mail. Hawking was interviewed on 8 April 1993 when he filmed his Trek appearance. This interview was part of the TNG Season 6 DVD special feature "Mission Overview Year Six" – "Descent – Part 1 Featuring Stephen Hawking".
Hawking visited the Star Trek: Deep Space Nine set during the filming of "The House of Quark". In the Star Trek: Deep Space Nine Companion (p. 171), Armin Shimerman describes meeting Dr. Hawking as one of the high points of his life.
Hawking also played himself on Futurama, The Simpsons, and The Big Bang Theory, and appeared in documentaries about Red Dwarf and Doctor Who. In 2010 he co-authored The Grand Design with former Star Trek: The Next Generation story editor and writer of the episode "The Dauphin", Leonard Mlodinow.
In later life, Hawking, along with Elon Musk, became one of the leading voices leveled against the unchecked development of real world artificial intelligence (AI), warning it could be the "worst event in the history of our civilization," if creators and developers do not "employ [the] best practice and effective management" as humanly and technologically possible.