Carl David Tolmé Runge (30 August 1856 – 3 January 1927) was a German mathematician, physicist, and spectroscopist.

He was co-developer and co-eponym of the Runge–Kutta method in the field of what is today known as numerical analysis.

He spent the first few years of his life in Havana, where his father Julius Runge was the Danish consul. The family later moved to Bremen, where his father died early (in 1864).

In 1880, he received his Ph.D. in mathematics at Berlin, where he studied under Karl Weierstrass. In 1886, he became a professor in Hannover, Germany.

His interests included mathematics, spectroscopy, geodesy, and astrophysics. In addition to pure mathematics, he did a great deal of experimental work studying spectral lines of various elements (together with Heinrich Kayser), and was very interested in the application of this work to astronomical spectroscopy.

In 1904, on the initiative of Felix Klein he received an appointment to the Georg-August University of Göttingen, which he accepted. There he remained until his retirement in 1925.

The crater Runge on the Moon is named after him.