Gary McKinnon is a British hacker known for his unauthorized access to U.S. military and NASA computers between 2001 and 2002. He claimed to be searching for evidence of UFOs and government cover-ups related to extraterrestrial life. His actions led to significant legal consequences and a lengthy extradition battle with the United States. McKinnon's hacking activities were described as the "biggest military computer hack of all time." He faced charges that could have resulted in a lengthy prison sentence, but in 2012, the UK government decided not to extradite him due to health concerns, including his diagnosis of Asperger's syndrome.