He is the founder of buffer overflow attacks and the first computer worm in internet which is named Morris Worm, not only that but he is also a co-founder od ViaWeb(Now it is called as Yahoo! Store) which is the first web-based application which lets users to create their own online store with very little effort and less expertise. According to Morris the worm created by him is intended to gauge the size of internet, but when it comes to real the worm has the capable to find the vulnerability's of the targeted systems and which in turn gives access to hackers by exploiting the security hole.
The creation of this worm made him the first person to be prosecuted and convicted in US under the Computer Fraud and Abuse Act and sentenced for 3years of prohibition, 400hours of community service, $10,050 fine and his supervision costs.
After this he has achieved many things like being a cofounder of ViaWeb which was sold to yahoo for $48million, Receiving a Ph.D in Applied science by Harvard, being a professor in MIT(Massachusetts Institute of Technology) and so on which made him special in this world.
Loyd Blankenship(a.k.a +++The Mentor+++)
Loyd Blankenship is well know as The Mentor and written as +++The Mentor+++, In 1970s he is a well-known hacker and writer and is also very very famous for his The Hackers Manifesto and was published in the underground hacker ezine Phrack and you can read it from here. Loyd gave a reading of The Hacker Manifesto and offered additional insight at H2K2. (Source: Wikipedia - http://en.wikipedia.org/wiki/Loyd_Blankenship)
Jonathan James(a.k.a c0mrade)
Jonathan was the first juvenile to be sent to sentence at the age of 16. Jonathan is well known for his high rated intrusions including gaining access to DTRA(Defence Threat Reduction Agencies) servers and installing a backdoor which in-turn gave him access to sensitive email and passwords of their employees and 10 other military systems.
The other major intrusion is breaking in to NASA servers and stealing the software(Actually it is a source code) worth of $1.7 Million, This intrusion forced NASA to shutdown their systems for 4 weeks to find and fix the problem. The software that was steeled by J.J is used to support the physical environment in International Space Station.
J.J was died in May 18, 2008 by committing a suicide.
Kevin Poulsen(a.k.a Dark Dante)
Kevin Poulsen is also the most wanted and the best hacker once is US, Kevin is well known for his take over of all the telephone lines of Los Angeles Radio Station(KIIS-FM) by which he would be the guaranteed 102nd caller for which he will win the prize of a Porsche 944 S2. Later that when FBI started perusing him he went underground. When he was underground, the famous NBC featured a show called Unsolved Mysteries, at that time their 1-800 telephone lines are mysteriously crashed…. Later that incident Kevin was arrested for his actions and was sentenced for 51 months in prison and ordered to pay $56,000.