Stepan Andriyovych Bandera (Ukrainian: Степан Андрійович Бандера; 1 January 1909 – 15 October 1959) was a Ukrainian political activist and leader of the Ukrainian nationalist and independence movement.

In 1934, he was arrested in Lwów (in Ukrainian, Lviv) by Polish authorities and was tried twice: for involvement in the assassination of the Polish minister of internal affairs, Bronisław Pieracki; and at a general trial of Organization of Ukrainian Nationalists executives. He was convicted of terrorism and sentenced to death, but the sentence was commuted to life imprisonment.

In September 1939, while Poland was being invaded, under unclear circumstances Bandera managed to get freed from prison and proceeded to work, with German support, for an uprising in the Kresy. These eastern Polish territories had a majority Ukrainian population, and went on to become modern Western Ukraine. At the same time, he tried to stoke unrest in the Ukrainian Soviet Socialist Republic, modern Eastern Ukraine. His goal was to establish a unified Ukrainian state, composed of areas inhabited by ethnic Ukrainians, but that had been under the control of Poland and the Soviet Union.

On 30 June 1941, eight days after Germany's attack on the Soviet Union, Bandera in Lviv proclaimed an independent Ukrainian state. His militant branch of the Organization of Ukrainian Nationalists (OUN) thought that, in their struggle against the Soviet Union, they had a powerful ally in Nazi Germany. But the Germans arrested the newly formed Ukrainian government and sent them to concentration camps in Germany. Bandera was imprisoned by the Nazis until September 1944.

At that juncture, with the war going very badly against Germany, Bandera was released in the hope that he would fight the advancing Soviet forces. He established his headquarters in Berlin and received German financial, material, and personnel support for his Ukrainian Insurgent Army.

After the war, in 1959, in Munich, Germany, Bandera was assassinated by the Soviet KGB (secret police).

Assessments of his work have ranged from totally apologetic to sharply negative. On 22 January 2010, the outgoing President of Ukraine Viktor Yushchenko awarded Bandera the posthumous title of Hero of Ukraine. The award was condemned by European Parliament, Russian, Polish and Jewish organizations and was declared illegal by the following Ukrainian government and a court decision in April 2010. In January 2011, the award was officially annulled.

Stepan Bandera remains a controversial figure today both in Ukraine and internationally.