Alexander Valterovich Litvinenko (30 August 1962 (at WebCite) or 4 December 1962 – 23 November 2006) was a British-naturalised Russian defector and former officer of the Russian Federal Security Service who specialised in tackling organised crime.

Alexander Litvinenko was an officer of the Russian Federal Security Service and its predecessor, the KGB, until he left the service and fled the country in late 2000.