Detractors regard him as a man driven more by his own ego and a desire to cock a snook at the Establishment he has spent much of his life fighting.
The Australian has admitted in the past that he came close to a breakdown after being tried on charges of illegal hacking in the mid 1990s, which also led to a bitter break-up with the mother of his baby son.
Mr Assange was spared a jail sentence in 1995 after admitting 25 charges of hacking into computer networks including the Canadian communications firm Nortel.
Ken Day, who headed the Operation Weather investigation into Mr Assange’s circle of hackers, told The Daily Telegraph: "Ego is a big part of who he is.
The challenge to win. I think that's important to him as a person. He wouldn't give up on a system he was trying to break into, he was very persistent.”