Without question, Stephen Hawking, the legendary theoretical physicist who died this week at 76, was not only the world’s best-known scientist but also one of the greatest scientific figures of all time.

Indeed, since 1979, he held the same professorial chair at Cambridge University once graced by Sir Isaac Newton — who, unlike his successor, never wrote a blockbuster international bestseller (1988’s “A Brief History of Time”) or appeared on “The Simpsons.”

Before Hawking became a pop-culture icon, he had done groundbreaking work on the Big Bang Theory. He rocked the world of astrophysics in 1974 by discovering that black holes give off radiation — something no one believed at the time. Two of the landmark scientific discoveries of the last century were general relativity and quantum mechanics; in his time, Hawking made tremendous strides toward unifying the two fields, bringing physics tantalizingly close to achieving its Holy Grail.

These accomplishments alone would have earned Hawking a prominent and permanent place in the scientific pantheon. But the truly staggering thing about what Hawking accomplished is that he did it all while suffering from severe disability. At 21, he was diagnosed with amyotrophic lateral sclerosis — Lou Gehrig’s disease — and given no more than two years to live.

The neuromuscular disease progressed so rapidly that by 1974, when he made his first great breakthrough, Hawking was confined to a wheelchair by paralysis and spoke in a nearly impenetrable slur. In 1985, an emergency tracheotomy robbed him of a voice entirely. Hawking communicated through a computerized device. By the end, his only lifeline from his corporeal tomb was the twitch of his cheek.

And yet, look what the man did with his lot. Had the indefatigable Hawking not defied the astronomical odds set against him by doctors, the loss to science would have been incalculable. Hawking was an intellectual hero, to be sure, but he was no secular saint. (Ask his first wife, who angered Hawking’s admirers by tarnishing his image with public tales from their tragic marriage.)

It can be difficult to see greatness in your own time, but the sheer spiritual audacity of this man, who refused to allow the prison of his ruined body to shackle his mind, stands as the scientific wonderworker’s greatest miracle.

Aside from being known as a brilliant scientist, Hawking was also known for his humor and wit, a sardonic form that pulled no punches. In an interview with British television personality Piers Morgan, he was asked about his IQ and responded, “People who boast about their IQ are losers.” Another time, when discussing making contact with alien forms, Hawking remarked, “I think it would be a disaster. The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low.”

When asked a few years back by the New York Times how he kept his spirits up, Hawking said, “My expectations were reduced to zero when I was 21. Everything since then has been a bonus.” The boundaries of his world were narrowly and severely drawn by disease, but with his mind — peerless, free and invincible — Stephen Hawking roamed the universe.