Stephen Timoshenko, Ukrainian-American engineer and academic (b. 1878)
Stepan Prokofyevich Timoshenko (Russian: Степан Прокофьевич Тимошенко; Ukrainian: Степан Прокопович Тимошенко, romanized: Stepan Prokopovych Tymoshenko; December 23, 1878 – May 29, 1972), later known as Stephen Timoshenko, was a Russian Imperial and later, an American engineer and academician of Ukrainian descent.

He is considered to be the father of modern engineering mechanics. An inventor and one of the pioneering mechanical engineers at the St. Petersburg Polytechnic University. A founding member of the Ukrainian Academy of Sciences, Timoshenko wrote seminal works in the areas of engineering mechanics, elasticity and strength of materials, many of which are still widely used today. Having started his scientific career in the Russian Empire, Timoshenko emigrated to the Kingdom of Serbs, Croats and Slovenes during the Russian Civil War and then to the United States.