Alexander Valterovich Litvinenko (Russian: Алекса́ндр Ва́льтерович Литвине́нко ) (30 August 1962 – 23 November 2006) was a former officer of the Russian State security service, and later a Russian dissident and writer.

Litvinenko became a KGB officer in 1986, and two years later, was moved into the Military Counter Intelligence. He was promoted to the Central Staff, and specialised in counter-terrorism and infiltration of organised crime. Six years later, he was promoted to senior operational officer and deputy head of the Seventh Section of the FSB.

In November 1998, Litvinenko publicly accused his superiors of ordering the assassination of Russian tycoon and oligarch, Boris Berezovsky. Litvinenko was arrested the following March on charges of exceeding his authority at work. He was acquitted in November 1999 but re-arrested before the charges were again dismissed in 2000. A third criminal case began but he fled the country to the United Kingdom with his wife, where he was granted political asylum. During his time in London Litvinenko authored two books, " Blowing up Russia: Terror from within " and " Lubyanka Criminal Group, " where he accused Russian secret services of staging Russian apartment bombings and other terrorism acts to bring Vladimir Putin to power. He also made a wide range of other claims against Russian secret services and Putin through interviews and articles he wrote.

On 1 November 2006, Litvinenko suddenly fell ill and was hospitalized. He died three weeks later from lethal poisoning by radioactive polonium-210. According to medical professionals, "Litvinenko’s murder represents an ominous landmark: the beginning of an era of nuclear terrorism."