There are two kind of hacker to consider: black hat and white hat. Julian Assange and Kevin Mitnick are black hat notorious hackers. Assange, of course, has been entrenched in the Venezuelan embassy in `London for other crimes but is reportedly still active on the internet.
Bycontrast after his arrest in 1995 Mitnick became white hat an has proved his worth to top flight security organisations. Joanna Rutowska has been an ethical hacker from the beginning. A Polish expert, she has revealed important weaknesses in data protection and the pain of malware.
The best hackers in the world are ones who have been able to hack into the computers of the federal government and major retail outlets. They have been to cause all kinds of havoc doing things such as transferring funds and just plain causing disruption to service. The first person that gained acclaim as a computer hacker was Kevin Mitnick. During the mid-1990's and when the internet first became the thing that it became, Mitnick was able to hack into Pentagon computers and several major retailers. He would spend five years in prison and today is a computer security consultant with several major companies. Some other well known hackers were Gary McKinnon, Matthew Bevan, LuluSec, and Adrian Lamo. All of these individuals have been known to have hacked into computers from all over the world. They also paid the ultimate price for their deeds by spending time in prison.