Eligiusz Niewiadomski was a Polish modernist painter and art critic who sympathized with the right-wing National Democracy movement. In 1922 he assassinated Poland's first President, Gabriel Narutowicz, in his first week in office as president.

Gabriel Narutowicz, the first president of Poland after regaining independence, was assassinated on 16 December 1922, five days after taking office, aged 57. He was fatally shot by Eligiusz Niewiadomski, an artist and art critic, while visiting an exhibition at Warsaw's Zachęta gallery.