Otto Haupt (born 5 March 1887 in Würzburg; died 10 November 1988 in Bad Soden) was a German mathematician.

Haupt obtained his PhD in 1911 under the supervision of Georg Rost and Emil Hilb at the University of Würzburg,^[1] and became a professor at the University of Erlangen-Nuremberg. He retired from teaching in 1953, but continued his mathematical research for many subsequent years.^[2]

Since 1918 he was married to Edith Hughes. Despite her Jewish ancestry, she survived the Nazi period unharmed in Erlangen, and lived to 1981.^[2]

Haupt specialized in geometry and real analysis; many of his research publications related to the four-vertex theorem on local minima and maxima of curvature. He also wrote textbooks on algebra and calculus.^[2]

In 1987, his centenary year, a birthday conference was given in his honor at the University of Erlangen.^[2][3]

He was awarded honorary doctorates from the University of Bonn, the University of Nantes and the University of Würzburg.^[2][3][4]