Theodore von Kármán (Hungarian: (szőllőskislaki) Kármán Tódor [(søːløːʃkiʃlɒki) ˈkaːrmaːn ˈtoːdor], May 11, 1881 – May 6, 1963) was a Hungarian-American mathematician, aerospace engineer, and physicist who worked in aeronautics and astronautics. He was responsible for crucial advances in aerodynamics characterizing supersonic and hypersonic airflow. The human-defined threshold of outer space is named the "Kármán line" in recognition of his work. Kármán is regarded as an outstanding aerodynamic theoretician of the 20th century.

Theodore von Kármán was born into a Jewish family in Budapest, then part of Austria-Hungary, as Kármán Tódor, the son of Helene (Konn or Kohn, Hungarian: Kohn Ilka) and Mór Kármán [eo]. Among his ancestors were Rabbi Judah Loew ben Bezalel, who was said to be the creator of the Golem of Prague, and Rabbi Moses Kunitz, who wrote about Zohar. His father, Mór, was a well-known educator, who reformed the Hungarian school system and founded Minta Gymnasium in Budapest. He became an influential figure and became a commissioner of the Ministry of Education, and was responsible for "planning an education of a young archduke, the Emperor's cousin". In 1907 Mór Karman was ennobled, Theodore later described it:

To receive a predicate of nobility, my father had to be landed. Fortunately he owned a small vineyard near Budapest, so the Emperor bestowed upon him the predicate "von Szőllőskislaki" (small grape). I have shortened it to von, for even to me, a Hungarian, the full title is almost unpronounceable.

Theodore had three brothers (among them Elemér Kármán [eo]) and one sister, Josephine. At age six, he could "perform large mental calculations", for example multiplication of six-digit numbers. Father discouraged Theodore's mathematical education, he was afraid that his son would be a child prodigy and a freak. He was tutored by his father and his father's former student; later he entered the Minta Gymnasium in Budapest. He won Eötvös Prize "for the best student in mathematics and science in the whole of Hungary" in his last year at Minta.

He studied engineering at the city's Royal Joseph Technical University (Budapest University of Technology and Economics). He graduated in 1902 with a degree in mechanical engineering, his thesis was "The motion of a heavy rod supported on its rounded end by a horizontal plane". He then served a year as an artillery cadet in the Austro-Hungarian army. In 1903-1906 he worked as an assistant at the Royal Joseph Technical University. In 1906 he moved to the German Empire and joined Ludwig Prandtl at the University of Göttingen, where he received his doctorate in 1908, for his research on "mathematical models for the buckling of large structures". He taught at Göttingen for four years. In 1913 he accepted a position as director of the Aeronautical Institute at RWTH Aachen University, a leading German university. His time at RWTH Aachen was interrupted by service in the Austro-Hungarian Army from 1915 to 1918, during World War I, when he designed the Petróczy-Kármán-Žurovec, an early helicopter.

After the war, in 1919, he returned to Aachen with his mother and sister Josephine. Some of his students took an interest in gliding and saw the competitions of the Rhön-Rossitten Gesellschaft as an opportunity to advance in aeronautics. Kármán engaged Wolfgang Klemperer to design a competitive glider.

Josephine encouraged her brother Theodore to expand his science beyond national boundaries. They organized the first international conference in mechanics held in September 1922 in Innsbruck. Subsequent conferences were organized as the International Union of Theoretical and Applied Mechanics.

In 1926, Karman was first invited to the USA by the California Institute of Technology to build a wind tunnel. In 1930 he was invited for a position of a full-time director of the Guggenheim Aeronautical Laboratory at California Institute of Technology (GALCIT); his mother and sister, Josephine, also moved to California.