Marcos Orlando Letelier del Solar (April 13, 1932 – September 21, 1976) was a Chilean economist, Socialist politician and diplomat during the presidency of Socialist President Salvador Allende. As a refugee from the military dictatorship of General Augusto Pinochet, Letelier accepted several academic positions in Washington, D.C., where he was assassinated by Pinochet's DINA agents in 1976.