Stephen Hawking was born in England in 1942 and is a world famous scientist.
He had a disease called ALS which stopped him controlling his muscles, so he had to use a wheelchair to get around and a speech synthesizer.
He appears in videogames, films and series such as The Simpsons, and has even sung with U2 and Pink Floyd!
But why is he so famous?
Stephen Hawking is a physicist and a cosmologist. He is well-known for his work on space and in particular black holes.
His theories explaining the origin and evolution of the universe made him famous with other scientists.
But he also wanted to make science accessible and attractive to others.
One of his books, in which he explains the universe in a simple way, has sold 9 million copies; a record!
He is also well-known to the general public because of his illness.
It prevents him from feeding himself, moving and speaking, but not from thinking about how vast the cosmos is.
With courage and humor, he shares his reflections and theories with specialists and children alike.
To express himself, he has to write each word, which is then read by a machine. Not easy, but he never gave up.
Stephen Hawking died on 14 March 2018 and was greatly admired, because in spite of his handicap, he never gave up trying to pass on his passion for science.