Edward Teller - the man behind America's nuclear powers
Edward Teller, the driving force behind American defence and energy policies for more than half a century, was never far from controversy.
As one of the most hawkish nuclear experts - the man who thought the atom bomb was not powerful enough - it is no surprise that he drew a large amount of criticism.
Teller exerted a profound influence on successive US administrations, championing the development of the atomic and hydrogen bombs, nuclear power and the controversial Strategic Defense Initiative, known as Star Wars.
He is credited with being the brains behind Star Wars, and with helping to persuade President Ronald Reagan to take up the project in the early 1980s.
The plans incorporated space-based laser systems to create the ultimate national defence shield.
Despite wide criticism for the project for its reliance on complex software and soaring cost estimates, Teller gave it his continued support.
In an interview in 2001, Teller showed his old fighting spirit, delivering the two-word endorsement - "High time!" - to President George W Bush's decision to pull out of the 1972 Anti-Ballistic Missile treaty with Russia to work on the Son of Star Wars defence project.
With his beetle brow and central European accent, Edward Teller was said to have been the model for Dr Strangelove, the mad scientist of Stanley Kubrick's film.
It was his interest in the development of nuclear weapons that was to have the greatest impact on the United States and the wider world.
By 1939, German scientists had discovered nuclear fission. This was to cause deep distrust in America and lead to the creation of the Manhattan Project to develop the atom bomb before Germany.
As early as 1940 Teller was advocating the development of the hydrogen bomb, generated by nuclear fusion, to create an even more devastating weapon.
Teller persuaded Truman to develop the fusion bomb
He finally persuaded the Truman administration to develop the fusion bomb following testing of the first Soviet atomic bomb in 1949. He felt vindicated in pursuing it.
But his boss Robert Oppenheimer and other colleagues at the Manhattan Project had opposed it.
More antagonism was to follow, which cost Robert Oppenheimer his career. He was accused of disloyalty on the basis of past associations and when his security clearance was revoked, many of his friends blamed Teller.
One of Teller's greatest legacies was to push for the creation of a national science laboratory, which after much lobbying, was opened in 1952.
Over the next few years the Lawrence Livermore Laboratory became a competitor in the development of nuclear deterrents to the Los Alamos laboratory in New Mexico.
It is said his pursuit of defence strategies was born through his own experiences of the 1919 communist revolution in his native Hungary and the rise of Nazism during his time in Germany in the 1930s.
Edward Teller was born on 15 January, 1908, in Budapest into an affluent Jewish family.
In 1926, he left Budapest to study chemical engineering in Karlsruhe, Germany. There he became interested in physics. He transferred to the University of Leipzig, receiving a PhD in physics in 1930.
When Adolf Hitler came to power in Germany, Teller realised there was no future for him. He left to work in Denmark and London, before travelling to the United States.
Throughout his career, Teller became a respected scientist, whose promotion of defence has left a lasting legacy on United States policy.
In his autobiography in 2001, he stated: "I deeply regret the deaths and injuries that resulted from the atomic bombings, but my best explanation of why I do not regret working on weapons is a question: What if we hadn't?"
Teller's wife Mici died in 2000.