Štefan Lux (4 November 1888 – 3 July 1936) was a Slovak Jewish journalist, and a Czechoslovak citizen, who committed suicide in the general assembly of the League of Nations during its session on 3 July 1936. He shot himself in order to alert the world leaders of the rising dangers of German antisemitism, expansionism, and militarism.

After shouting "C'est le dernier coup" ("This is the final blow"), he shot himself with a revolver. In his suicide note he begged the British foreign secretary Anthony Eden to do something to stop Germany's criminal regime. Eden was never shown the letter.

Condemning his act, but paying tribute to his cause, the journalist Léon Savary concluded: "People bold enough to fight for justice shouldn't kill themselves, but stay at their position."

His actions were misreported by the world media at the time.

Lux was also a writer, a theater actor, and a film director, who published his work under the pseudonym Peter Sturmbusch.

He was wounded on more than one occasion during World War I.