Salvador Allende Gossens (1908-1973) was a Chilean politician. He served as the democratically elected President of Chile from 1970 until his death in 1973, after a military coup led by Augusto Pinochet.
Allende was a Marxist, in fact the first one by democratic means, and was openly attempting to make Chile a socialist state. He palled about with the establishment communists of the era, for example by inviting Fidel Castro for a tour of Chile.
The Soviet Union made repeated demands that he introduce more hard-line measures, which as a democratically elected leader Allende was largely unwilling to do; however, his record was not entirely spotless, as shortly before the Pinochet coup, the Chilean legislature passed a resolution accusing his administration of unconstitutional activities, such as passing laws by decree, removing cabinet ministers from legislative oversight, harassing opposition media outlets, making illegal arrests, and torturing detainees. The legislature also implored the Chilean military to restore order (i.e., remove Allende, as Chile did not have a formal means of impeaching a president at the time).
Pinochet went on to do everything they accused Allende of and more, dissolving the legislature, appointing all judges, authorizing trial (with death sentences) by military courts, killing around 5,000 Chileans in the next 17 years (most "disappeared"), with thousands more imprisoned or fleeing the country. Milton Friedman went to Chile with his "Chicago Boys" to rehaul the economy, which with the military junta in power was easier to do. These reforms have been maintained under the following democratic administrations.
Henry Kissinger didn't like him very much, either. Richard Nixon specifically told the CIA to do something to get him out of power. The exact connections between the CIA and Pinochet's coup have never been exactly proved, but the connection is well-attested.