Boris Vyacheslavovich Gryzlov (Russian: Борис Вячеславович Грызлов, IPA: [bɐˈrʲiz ɡrɨˈzlof]; born 15 December 1950) is a Russian politician and diplomat currently serving as the Russian Ambassador to Belarus. Previously, he served as the chairman of the State Duma from 2003 to 2011 and as interior minister from 2001 to 2003. He was also the leader of the ruling United Russia party.

Gryzlov was born in Vladivostok but was raised in Leningrad (now Saint Petersburg). He graduated from the Leningrad Electrical Institute of Communications in 1973 and worked as a radio engineer. From 1977 to 1996, he worked his way up from being an engineer to division director in the Elektronpribor plant. He was not a public figure before 1999. In October 1999, he became head of the St Petersburg regional branch of Sergey Shoygu's Unity party, and in December 1999, he was elected to the State Duma running on the Unity party ticket. In January 2000, he was elected chairman of the Unity faction in the Duma.

In March 2001, he was appointed to the post of chief of Russian police and became Interior Minister. In this position, Gryzlov proclaimed that the fight against terrorism and corruption were his priorities.

Gryzlov supported the Kremlin's policies in Chechnya^[when?] and won the reputation of being a trusted and loyal supporter of the president.

In August 2001, Boris Gryzlov claimed that up to 100 industrial enterprises in Saint Petersburg, including the Petersburg Fuel Company, a leading gasoline retailing operator in the city, as well as the four main sea ports of Northwestern Russia, Saint Petersburg, Kaliningrad, Arkhangelsk and Murmansk, were controlled by the Tambov Gang. In May 2002, he sent a commission to St. Petersburg to investigate corruption allegations in the city's gasoline market. The investigation was initiated after the Faeton Gasoline Company, the second leading fuel retailing company in the city, had complained to both Gryzlov and the Prosecutor General's Office in April that the Saint Petersburg City Administration had given preferential treatment to the Petersburg Fuel Company.

Within a year, he returned to party politics, and in November 2002, became the head of the United Russia, a centrist pro-Putin group what emerged from Unity and several other pro-government movements that joined it. In December 2003, Boris Gryzlov was elected as speaker of the Duma.

In November 2009, Gryzlov defined United Russia's ideology as "Russian conservatism" – characterizing such conservatism as "an ideology of stability and development, constant creative renovation of society without stagnation and revolutions." Gryzlov resigned from the office of Parliament speaker on 14 December 2011, amongst accusations of polling fraud orchestrated by the United Russia party in the 2011 Russian Duma elections.

He was sanctioned by the UK government in 2014 in relation to the Russo-Ukrainian War.