In 2000, a 15 year old took down the websites of Yahoo!, Amazon, E*TRADE, Ebay, CNN, and more.

His Internet alias was “Mafiaboy,” but in real life he’s called Michael Demon Calce. He was known as the Quebec teenager who successfully carried out several denial of service attacks against multiple websites. His interest in computers began at a very young age. 

His parents divorced, so his dad bought him a computer so they could stay in touch. He instantly became fascinated with the computer, namely how he was in charge of its every function, and the sense of control it gave him. On February 7, 2000, Calce targeted Yahoo! by overloading their servers until they shut down.

According to Calce, his goal was to establish dominance for him and his cybergroup. The website buy.com was shut down in response, so Calce brought down multiple other sites over the following week. The US FBI and Royal Canadian Mounted Police caught onto him when he started claiming in IRC chatrooms that he was responsible.

He was caught and sentenced on September 12, 2001 to eight months of “open custody,” one year of probation, restricted use of the Internet, and a small fine. While back then, charges for such actions were considerably lighter, in today’s world doing something similar could result in pretty serious jail time- and if you’re good enough, being hired by a corporation or government branch after. 

(Source)