Dr. Wacław Olszak (29 May 1868 – 11 September 1939) was a Polish physician, activist and politician from the region of Zaolzie, Czechoslovakia. He was a mayor of the town of Karviná for seven years. Ten days after outbreak of World War II he was murdered by Nazis. Streets in Cieszyn and Karviná are named after him. His son Wacław became an internationally acclaimed engineer and construction theorist; his son Feliks became a metallurgical engineer.