Stephen Hawking was a renowned English theoretical physicist and cosmologist known for his work on black holes and relativity. He was diagnosed with ALS at a young age but continued his scientific work despite being wheelchair-bound and later losing his ability to speak. Through innovative assistive technology, Hawking was able to communicate and continue his groundbreaking research on theoretical physics and cosmology. He became one of the most influential scientists of the 20th century and authored several popular science books explaining complex concepts to the general public.