Jovan Simonov Plamenac (Serbian Cyrillic: Јован Симонов Пламенац; 1873–1944) was a Montenegrin politician.
Starting out as a prominent leader of the True People's Party in the Principality of Montenegro, state that would soon transform into a kingdom, Plamenac was a staunch supporter of the country's monarch Prince Nikola Petrović-Njegoš who changed his role to king in 1910. As World War I broke out and King Nikola secretly fled the country after it got invaded by the Central powers, Plamenac denounced the king.
Following the war, Plamenac became one of the leaders of the Greens and a chief protagonist of the 1919 Christmas Rebellion in opposition to the post-war Montenegrin unification with Serbia and subsequent creation of the Kingdom of Serbs, Croats and Slovenes. Upon fleeing to Italy in wake of the failed rebellion, Plamenac became head of the Montenegrin authorities in exile. At the post he presided over units of exiled Greens who trained in the town of Gaeta with Italian support before being covertly shipped back home across the Adriatic where a low-level guerilla insurgency continued even after the failed rebellion. Plamenac also tried to gain political support abroad for his organization's opposition to the newly created South Slavic state, but achieved very little in that regard.
By mid-1920s, Plamenac did a complete turnaround, deciding to cut a deal with the Kingdom of SCS authorities, which allowed him to return home where he became a centrist politician with Serbian People's Radical Party of Nikola Pašić.
He ended up as a World War II Nazi collaborator whose activity during the war is highly disputed and controversial.