Vladimir Yefimovich Semichastny (Russian: Владимир Ефимович Семичастны?, born 1924) was the head of the KGB from November 1961 to April 1967.

Semichastny, like his mentor and predecessor Alexander Shelepin, was involved in a number of embarrassing incidents involving the KGB. For example, he sanctioned the arrest of Professor Frederick Barghoorn of Yale University when he was visiting Moscow in October 1963. Semichastny hoped that by charging Barghoorn as a spy he could induce the United States to release Igor Ivanov, arrested by the Federal Bureau of Investigation that month for espionage.

Barghoorn was a personal friend of President John F. Kennedy, who forcefully stated that Barghoorn was not involved in any illegal activites at a press conference. The Soviets were humiliated and quickly released Barghoorn. Ivanov was allowed to leave the United States in 1971.

Subsequently, Semichastny participated in the ouster of Soviet leader Nikita Khrushchev in October 1964, an act that undoubtedly led to his being retained by the new Soviet leadership. There are some indications that Leonid Brezhnev, who led the coup against Khrushchev, wanted to assassinate him, but Semichastny refused to allow KGB participation.

"many young Communist Party and Communist Youth League workers have joined the KGB and none of the people who, during the time of the personality cult of Joseph Stalin, took part in the repressions against innocent Soviet people is now in the Service."

Brezhnev finally replaced Semichastny on May 181967, as part of a Kremlin power shuffle. Yuri Andropov, the new chief of the KGB, had the task of rebuilding the image and effectiveness of the service.