Vsevolod Nikolayevich (Boris) Merkulov (Всеволод Николаевич Меркулов in Russian) (Template:OldStyleDate, Zagatala, present-day Azerbaijan – December 23, 1953), was the head of NKGB from February to July 1941, and again from April 1943 to March 1946. He was a member of the so-called "Georgian mafia" of Lavrenti Beria, head of the NKVD.
In 1913, Merkulov graduated from the Tiflis Gymnasium with the gold medal and became a student at St. Petersburg University, Department of Physics and Mathematics. From 1921-1922, he worked as a detective at the Transportation Unit of the Cheka in Georgia. From 1925-1931, Merkulov held the posts of Head of Secret Operations Directorate and Deputy Head of GPU of Adzharistan.
Merkulov was People's Commissar of State Security of the USSR from February 3, 1941 until July 20, 1941, when the NKGB again fell under control of the NKVD as GUGB. From 1941-1943, Merkulov was Deputy People's Commissar of the NKVD. In 1943 the GUGB was again separated from the NKVD, and Merkulov became head of the NKGB from July 20, 1943 until 1946.
He briefly served as Minister of the MGB in 1946, but was soon replaced by his rival Viktor Abakumov. Merkulov later served as Minister of State Control, replacing Lev Mekhlis. He was arrested and executed by firing squad along with his patron Beria and five other associates on December 23, 1953. It is rumored that all six bodies were cremated and buried in an unknown location near Moscow.
Merkulov may be best known for a letter he wrote to his boss, Laventri Beria, on October 2, 1944 regarding the cooperation the Soviet Union had received from a top scientist in the United States' program to develop an atomic bomb.