Eduard Karplus (September 7, 1899 – August ?, 1979) was an Austrian-born engineer, best known as the inventor of the Variac. Karplus was born in Hinterbrühl, the second child of Johann Paul Karplus, a neurophysiologist and psychiatrist, and Valerie von Lieben, a sister of physicist Robert von Lieben. He had thee brothers, Johann (Hans) Karplus (father of 2013 Nobel Laureate in Chemistry, Martin Karplus), Walter Gottlieb Karplus and Heinrich Karplus. He was a member of the American Institute of Electrical Engineers and a Fellow of the Institute of Radio Engineers (since 1938).