# In 1953, the CIA helped overthrow Muhammad Mussadegh, the elected prime minister of Iran; he was replaced by the Shah.

# In 1954, the CIA organized the ouster of Guatemalan President Jacobo Arbenz Guzman, and his replacement by a military dictator.

# In 1960, the CIA helped undermine Prime Minister Patrice Lumumba, the only legitimately elected leader in Congolese history. He was killed the following year. The corrupt and brutal dictatorship of Mobutu Sese Seko dominated Congo (which he renamed Zaire) for decades.

# In 1973, the CIA conspired against Chilean President Salvador Allende, who committed suicide after being overthrown by Gen. Augusto Pinochet.

(source)

Also, Saddam Hussein was installed as the leader of Iraq by the U.S., though the government we overthrew was not a democracy.