Konstantin "Koča" Popović was a Yugoslav politician and communist volunteer in the Spanish Civil War, 1937–1939 and Divisional Commander of the First Proletarian Division of the Yugoslav Partisans. He is on occasion referred to as "the man who saved the Yugoslav Partisans", because it was he who anticipated the weakest point in the Axis lines on the Zelengora–Kalinovik axis, and devised the plan for breaking through it during the Battle of Sutjeska, thus saving Tito, his headquarters and the rest of the resistance movement. After the war, he served as the Chief of the General Staff of the Yugoslav People's Army, before moving to the position of Foreign Minister and spent the final years of his political career as the Vice President of Yugoslavia.
Despite being a member of the Communist Party of Yugoslavia, he was a supporter of free-market reforms and was also a member of a group of Serbian liberals, a prominent political movement in the 1970s, which also included Marko Nikezić and Latinka Perović. He retired in 1972, amidst pressure against his group of liberals.