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1. Kevin Mitnick

 A seminal figure in American hacking, Kevin Mitnick got his career start as a teen. In 1981, he was charged        with stealing computer manuals from Pacific Bell. In 1982, he hacked the North American Defense                Command (NORAD), an achievement that inspired the 1983 film War Games. In 1989, he hacked Digital Equipment Corporation's (DEC) network and made copies of their software. Because DEC was a leading computer manufacturer at the time, this act put Mitnick on the map. He was later arrested, convicted and sent to prison. During his conditional release, he hacked Pacific Bell's voicemail systems.

Throughout his hacking career, Mitnick never exploited the access and data he obtained. It's widely believed that he once obtained full control of Pacific Bell's network simply to prove it could be done. A warrant was issued for his arrest for the Pacific Bell incident, but Mitnick fled and lived in hiding for more than two years. When caught, he served time in prison for multiple counts of wire fraud and computer fraud.

1. Although Mitnick ultimately went white hat, he may be part of the both-hats grey area. According to Wired, in 2014, he launched "Mitnick's Absolute Zero Day Exploit Exchange," which sells unpatched, critical software exploits to the highest bidder.

2. 2. Anonymous

   Anonymous got its start in 2003 on 4chan message boards in an unnamed forum. The group exhibits little organization and is loosely focused on the concept of social justice. For example, in 2008 the group took issue with the Church of Scientology and begin disabling their websites, thus negatively impacting their search rankings in Google and overwhelming its fax machines with all-black images. In March 2008, a group of "Anons" marched passed Scientology centers around the world wearing the now-famous Guy Fawkes mask. As noted by The New Yorker, while the FBI and other law enforcement agencies have tracked down some of the group's more prolific members, the lack of any real hierarchy makes it almost impossible to identify or eliminate Anonymous as a whole.

3. 3. Adrian Lamo

   In 2001, 20-year-old Adrian Lamo used an unprotected content management tool at Yahoo to modify a Reuters article and add a fake quote attributed to former Attorney General John Ashcroft. Lamo often hacked systems and then notified both the press and his victims. In some cases, he'd help clean up the mess to improve their security. As Wired points out, however, Lamo took things too far in 2002, when he hacked The New York Times' intranet, added himself to the list of expert sources and began conducting research on high-profile public figures. Lamo earned the moniker "The Homeless Hacker" because he preferred to wander the streets with little more than a backpack and often had no fixed address.

4. 4. Albert Gonzalez

   According to the New York Daily News, Gonzalez, dubbed "soupnazi," got his start as the "troubled pack leader of computer nerds" at his Miami high school. He eventually became active on criminal commerce site Shadowcrew.com and was considered one of its best hackers and moderators. At 22, Gonzalez was arrested in New York for debit card fraud related to stealing data from millions of card accounts. To avoid jail time, he became an informant for the Secret Service, ultimately helping indict dozens of Shadowcrew members.

   During his time as a paid informant, Gonzalez continued his in criminal activities. Along with a group of accomplices, Gonzalez stole more than 180 million payment card accounts from companies including OfficeMax, Dave and Buster's and Boston Market. The New York Times Magazine notes that Gonzalez's 2005 attack on US retailer TJX was the first serial data breach of credit information. Using a basic SQL injection, this famous hacker and his team created back doors in several corporate networks, stealing an estimated $256 million from TJX alone. During his sentencing in 2015, the federal prosecutor called Gonzalez's human victimization "unparalleled."

5. 5. Matthew Bevan and Richard Pryce

   Matthew Bevan and Richard Pryce are a team of British hackers who hacked into multiple military networks in 1996, including Griffiss Air Force Base, the Defense Information System Agency and the Korean Atomic Research Institute (KARI). Bevan (Kuji) and Pryce (Datastream Cowboy) have been accused of nearly starting a third world war after they dumped KARI research onto American military systems. Bevan claims he was looking to prove a UFO conspiracy theory, and according to the BBC, his case bears resemblance to that of Gary McKinnon. Malicious intent or not, Bevan and Pryce demonstrated that even military networks are vulnerable.

6. 6. Jeanson James Ancheta

   Jeanson James Ancheta had no interest in hacking systems for credit card data or crashing networks to deliver social justice. Instead, Ancheta was curious about the use of bots—software-based robots that can infect and ultimately control computer systems. Using a series of large-scale "botnets," he was able to compromise more than 400,000 computers in 2005. According to Ars Technica, he then rented these machines out to advertising companies and was also paid to directly install bots or adware on specific systems. Ancheta was sentenced to 57 months in prison. This was the first time a hacker was sent to jail for the use of botnet technology.

7. 7. Michael Calce

   In February 2000, 15-year-old Michael Calce, also known as "Mafiaboy," discovered how to take over networks of university computers. He used their combined resources to disrupt the number-one search engine at the time: Yahoo. Within one week, he'd also brought down Dell, eBay, CNN and Amazon using a distributed-denial-of-service (DDoS) attack that overwhelmed corporate servers and caused their websites to crash. Calce's wake-up call was perhaps the most jarring for cyber crime investors and internet proponents. If the biggest websites in the world—valued at over $1 billion—could be so easily sidelined, was any online data truly safe? It's not an exaggeration to say that the development of cyber crime legislation suddenly became a top government priority thanks to Calce's hack.

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