Hawking was diagnosed with a slow-progressing form of amyoptrophic lateral sclerosis (ALS) which gradually saw him paralysed.
His 1988 book "A Brief History of Time" sought to explain to non-scientists the fundamental theories of the universe and it became an worldwide bestseller, bringing him global acclaim.
Considered by many to be the world's greatest living scientist, Hawking was also a cosmologist, astronomer, mathematician and author of numerous books including the landmark "A Brief History of Time", which has sold more than 10 million copies.
Professor Stephen Hawking appeared via hologram to address an audience at the Sydney Opera House in April 2015.
Stephen William Hawking was born in Oxford on 8 January 1942.
"We are deeply saddened that our beloved father passed away today", Hawking's children, Lucy, Robert and Tim, said in a statement.
India's Prime Minister Narenda Modhi said Hawking's "grit and tenacity" inspired generations of people throughout the world.
He also explained that he was able to change the accent of his computer when the technology advanced, but he decided against it.
The account garnered one million fans within its first few hours and now has almost five million, with his infrequent posts typically generating tens of thousands of admiring comments and earning him the affectionate nickname "Hawking Dada", or "Uncle Hawking".
A man of great humour, he became a popular ambassador for science and was always careful to ensure that the general public had ready access to his work. "I'll tweet more tomorrow when I have the measure of it, but what an immeasurable life he had".
The famed scientist was married and divorced twice.
As he was preparing to marry his first wife, Jane, in 1964 his doctors gave him no more than two or three years of life.
Hawking discovered the phenomenon which became known as Hawking radiation, where black holes leak energy and fade to nothing.
But that's not the only major contribution or discovery that Hawking will be remembered for. After that, he tied the knot with his nurse, Elaine Mason, with whom Hawking spent his next 11 years.
"Alongside the benefits, AI will also bring dangers, like powerful autonomous weapons, or new ways for the few to oppress the many", Hawking said in 2016, at the opening of a new AI research centre at Cambridge University.
In September 2016 Hawking joined 375 "concerned" scientists in penning an open letter criticizing then-presidential candidate Donald Trump, citing the threat of climate change and blasting his push for the U.S. to leave the Paris Accord.
"We have lost a colossal mind and a wonderful spirit".
"His passing has left an intellectual vacuum in his wake", said Neil deGrasse Tyson. "He once said, aIt would not be much of a universe if it wasn't home to the people you love.' We will miss him for ever", the statement added.