Sepp Oerter (24 September 1870 – 14 December 1928) was a German politician and journalist. As a young man he was an activist member of various anarchist groups. He later moved over to socialist groupings and parties, including the Social Democratic Party (SPD) and, after the SPD split, the anti-war Independent Social Democratic Party ("Unabhängige Sozialdemokratische Partei Deutschlands" / USPD). During and directly after the revolution, for two months during the first half of 1919 and then for more than a year during 1920/21, he served as head of the regional government / Minister-president in the Free State of Braunschweig (Brunswick). By the time of his death he had broken with the political left and joined the National Socialists.