Thomas Hercules Karamessines (July 25, 1917 – September 4, 1978) was the Deputy Director for Plans of the United States Central Intelligence Agency from July 31, 1967 until February 27, 1973. Karamessines was actively involved in the Agency's Project FUBELT to undermine the government of Chilean president Salvador Allende.
Karamessines was born in New York City. He graduated from Columbia University in 1938 and from Columbia Law School in 1940. From 1941 to 1942, he served as a deputy district attorney for New York County with Thomas Dewey.
Karamessines served in the United States Army during the Second World War, but because of his knowledge of Greek language and history was assigned to the Office of Strategic Services (OSS), an organization that eventually would transform into the Central Intelligence Agency in 1948.
Karamessines started out his intelligence career as analyst for the Greek Desk OSS/X2 (Counter-Intelligence) following the liberation of Greece. After the dissolution of the OSS in October 1945, Karamessines stayed on as the director of intelligence for the US Embassy, possibly at the request of Lincoln MacVeagh. He became a member of the CIA after that organization was established in September 1947 and eventually CIA Station Chief in Athens. Karamessines came to work in the Office of Policy Coordination (OPC), the espionage and counter-intelligence branch of the CIA created in 1948, directed by Frank Wisner. The OPC concentrated on "propaganda, economic warfare; preventive direct action, including sabotage, anti-sabotage, demolition and evacuation measures; subversion against hostile states, including assistance to underground resistance groups, and support of indigenous anti-Communist elements in threatened countries of the free world." As chief American intelligence officer during the Greek Civil War, Karamessines was instrumental in organizing the Greek Central Intelligence Agency (KYP) along American lines. Karamessines worked undercover in Greece until 1953, and was Chief of Station in Rome from 1959-63 before being appointed Assistant Deputy Director for Plans under Richard Helms, holding the same post under Desmond FitzGerald. When the latter died of a heart attack in July 1967, Karamessines succeeded him as Director for Plans (with Cord Meyer serving as the Deputy Director for Plans).