It appears Hawking died early Wednesday. His 3 children released a statement saying, "We are deeply saddened that our beloved father passed away today."

Hawking had suffered from a rare early-onset form of ALS most of his life, which left him wheelchair-bound and almost entirely paralyzed. He could still communicate with the aid of a computer and the muscles in his cheek.

The world-renowned British scientist wrote several landmark books, including "A Brief History of Time." His black hole theories and discoveries were so vast ... the radiation that comes from them is called Hawking radiation.

Stephen guest starred on several TV shows as himself, such as "The Simpsons" and "The Big Bang Theory." He was also written into an episode of "Family Guy," but Seth MacFarlane did the voice.

The 2014 movie about his life, "The Theory of Everything," was nominated for Best Picture, and Eddie Redmayne, who played Hawking, won the Oscar for Best Actor.

Hawking had reportedly turned down Knighthood, and, amazingly, never won the Nobel Prize. He was awarded the Presidential Medal of Freedom here in the U.S.

Hawking was 76.