Stephen Hawking was a British theoretical physicist known for his groundbreaking work in the field of cosmology, particularly on the study of black holes. He was diagnosed with amyotrophic lateral sclerosis (ALS) at the age of 21 and was gradually paralyzed, eventually communicating through a speech-generating device. Hawking authored several popular science books including "A Brief History of Time" and "The Universe in a Nutshell", and was awarded numerous awards and honors, including the Presidential Medal of Freedom. He passed away on March 14, 2018, at the age of 76.