Karl Menger was an Austrian-American mathematician who worked on algebras, geometries, curve and dimension theory. He also contributed to game theory and social sciences.

Karl Menger's father, Carl Menger (1840-1921) was a famous economist, a professor at the University of Vienna, and founder the Austrian School of Economics. Karl's mother was Hermine Andermann (1869-1924), a journalist, author and musician. Carl was Roman Catholic and Hermine was Jewish so, although they lived together, the two could not marry (all marriages in Austria at this time were religious ceremonies). When their only child Karl (the subject of this biography) was born in 1902 this was seen as unacceptable by the Viennese social conventions and Carl was forced to withdraw from public life. He stopped teaching at the University of Vienna as soon as his son was born and he resigned his chair at the University a year later. Carl applied to Emperor Franz Joseph of Austria to have his son Karl made legitimate and his request was eventually granted. Twenty-five years earlier, Carl Menger had given Franz Joseph a three month course on economics.