Stepan Andriyovych Bandera was a Ukrainian far-right leader of the radical militant wing of the Organization of Ukrainian Nationalists (OUN-B).

The Organisation of Ukrainian Nationalists was a Ukrainian nationalist organization established in 1929 in Vienna, uniting the Ukrainian Military Organization with smaller, mainly youth, radical nationalist right-wing groups. The OUN was the largest and one of the most important far-right Ukrainian organizations operating in the interwar period on the territory of the Second Polish Republic. The OUN was mostly active preceding, during, and immediately after the Second World War. Its ideology has been described as having been influenced by the writings of Dmytro Dontsov, from 1929 by Italian fascism, and from 1930 by German Nazism. The OUN pursued a strategy of violence, terrorism, and assassinations with the goal of creating an ethnically homogenous and totalitarian Ukrainian state.