Edmund Georg Hermann Landau (14 February 1877 – 19 February 1938) was a German mathematician who worked in the fields of number theory and complex analysis.

Edmund Landau was born in Berlin. His father was Leopold Landau, a gynecologist and his mother was Johanna Jacoby. Landau studied mathematics at the University of Berlin and received his doctorate in 1899 and his habilitation (the post-doctoral qualification required in German universities) in 1901. His doctoral thesis was 14 pages long. In 1905 he married Marianne Ehrlich, the daughter of the biologist Paul Ehrlich, who was awarded the 1908 Nobel Prize in Physiology or Medicine.

Landau taught at the University of Berlin from 1899 until 1909 and held a chair at the University of Göttingen from 1909 onwards. Himself Jewish, in the 1920s Landau was instrumental in establishing the Mathematics Institute at the nascent Hebrew University of Jerusalem. Landau taught himself Hebrew, with the intent of eventually settling in Jerusalem. At the groundbreaking ceremony of the Hebrew University on April 2, 1925 he lectured in Hebrew on the topic Solved and unsolved problems in elementary number theory. He negotiated with the President of the University, Judah Magnes, regarding the details of his position at the University and the building that was to house the Mathematics Institute. In 1927 Landau and his family emigrated to Palestine, and he began teaching at the Hebrew University. The Landau family had difficulty adjusting to the primitive living standards then available in Jerusalem. In addition, Landau became a pawn in a struggle for control of the University between Magnes and Chaim Weizmann and Albert Einstein. Magnes suggested that Landau be appointed rector of the University, but Einstein and Weizmann supported Selig Brodetsky. Landau was disgusted by the dispute, not of his own making, and he decided to return to Göttingen. He remained there until he was forced out by the Nazi regime after the Machtergreifung in 1933 and thereafter he lectured only outside of Germany. In 1934 he moved to Berlin, where he died in early 1938 of natural causes.

In 1903 Landau gave a much simpler proof than was then known of the prime number theorem and later presented the first systematic treatment of analytic number theory in the Handbuch der Lehre von der Verteilung der Primzahlen,[1] or simply the Handbuch. He also made important contributions to complex analysis.

G. H. Hardy wrote that no one was ever more passionately devoted to mathematics than Landau.