Erich Rudolf Alexander Regener (12 November 1881 – 27 February 1955) was a German physicist known primarily for the design and construction of instruments to measure cosmic ray intensity at various altitudes.

He is also known for predicting a 2.8 K Cosmic microwave background,[1] for the invention of the scintillation counter which contributed to the discovery of the structure of the atom, for his calculation of the charge of an electron and for his early work on atmospheric ozone.

[2] Bruno Rossi wrote of this period that "In the late 1920s and early 1930s the technique of self-recording electroscopes carried by balloons into the highest layers of the atmosphere or sunk to great depths under water was brought to an unprecedented degree of perfection by the German physicist Erich Regener and his group.

In 1939 he was invited to work at the German Army-Air Force rocket research station in Peenemünde where he developed a spectrograph protected by a steel casing.

He was also cofounder of the Max Planck Institute for Solar System Research with Walter Dieminger and was instrumental in attracting physicists back to post-war Germany.