Leon Frank Czolgosz (Polish pronunciation: ) (May 1873 – October 29, 1901; also used his mother's maiden name "Nieman" and variations thereof) was the assassin of U.S. President William McKinley. In the last few years of his life, he claimed to have been heavily influenced by anarchists such as Emma Goldman and Alexander Berkman.
One of seven children of Polish immigrants, Czolgosz was born in Alpena, Michigan in 1873 to Victoria and Romeo Czolgosz. He was baptized in St. Albertus Catholic Church. His family moved to Detroit when he was five years old, and at the age of sixteen he was sent to work in a glass factory in Natrona, Pennsylvania for two years before moving back home..
According to a source, Czolgosz's ancestors were immigrants from what is now Belarus. It is very likely that Czolgosz's ancestors were both Belarussian and Polish, as the area of and between these now independent nations has historically been controlled by Russia, with borders changing at the whims of Russian rulers. Furthermore, the Russian government often relocated large groups of people to organize them by what it considered to be the people's ethnicities. His father emigrated to the US in the 1860s from Astravets near Hrodna. At immigration he stated his ethnicity as Hungarian and changed his surname from Zholhus (Жолгусь, Żołguś) to Czolgosz.