Gary McKinnon (born 10 February 1966) is a Scottish hacker facing extradition to the United States on charges of perpetrating what one US prosecutor claims is the "biggest military computer hack of all time."

Following legal hearings in the UK it was decided in July 2006 that he should be extradited to the US. In February 2007 his lawyers argued against the ruling in an appeal to the High Court in London, which was turned down on 3 April. On 30 July 2007 the House of Lords agreed to hear the appeal and on 17 June 2008 the Law Lords began hearing the case. This Judgment was delivered on 30 July 2008 with the Law Lords judging that Gary McKinnon could be extradited to the United States. He was given two weeks to appeal to the European Court of Human Rights before extradition, but the Court halted the extradition for an additional two weeks to allow time to hear his appeal on August 28, which was subsequently rejected.

His legal team subsequently decided to lodge another appeal, which was granted, based on the fact that McKinnon had been diagnosed with Asperger's syndrome. His diagnosis was made in August 2008 by the Cambridge University psychologist Prof Simon Baron-Cohen.