Karl Schwarzschild (October 9, 1873 - May 11, 1916) was a noted German Jewish physicist and astronomer, father of astrophysicist Martin Schwarzschild.

He was born in Frankfurt am Main. Something of a child prodigy he had a paper on orbits published when he was only sixteen. He studied at Strasbourg and Munich, obtaining his doctorate in 1896 for a work on Jules Henri Poincaré's theories.

From 1897 on he worked as assistant at the Kufner Sternwarte in Vienna, where he developed a formula to calculate the properties of photographic material involving an exponent now know as the Schwarzschild-exponent (p in formula below).

From 1901 until 1909 he was a professor at the prestigious institute at Göttingen, where he had the opportunity to work with some significant figures including David Hilbert and Hermann Minkowski. He moved to a post at the Astrophysical Observatory in Potsdam in 1909.

At the outbreak of World War I in 1914 he joined the German army despite being over 40 years old and served on both the western and eastern fronts, rising to the rank of lieutenant in the artillery.

While serving in Russia in 1915, he wrote two main papers, one on relativity theory and one on quantum theory. His work on relativity produced the first exact solutions to the general gravitational equations - one for non-rotating spherically symmetric bodies and one for static isotropic empty space surrounding any massive body. From the second he undertook some pioneering work on classical black holes. Two properties of black holes have been given his name - the Schwarzschild metric and the Schwarzschild radius. The papers were sent to Einstein and were later published in the Sitzungsberichte der Preussischen Akademie der Wissenschaften.

In astronomy he undertook measurements of variable stars, using photography. He also worked on improving optical systems, devising a perturbation equation to investigate geometrical aberrations.

He is said to have died either of an illness contracted while serving in Russia during the Great War or of a "rare metabolic disorder".