Mykola Stsiborskyi, also may be spelled Stsiborsky, Stsyborsky, Ściborski, or Sciborski was a Ukrainian nationalist politician who served on the Provid, or central leadership council of the Organization of Ukrainian Nationalists (OUN), and who was its chief theorist. He sided with Andriy Melnyk when the OUN split into two hostile factions, and was likely murdered by followers of Melnyk's rival Stepan Bandera.

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.