Rudolf Walter Ladenburg (June 6, 1882 in Kiel – April 6, 1952 in Princeton, New Jersey) was a German atomic physicist.

When the wave of German emigration began in 1933, he was the principal coordinator for job placement of exiled physicists in the United States.

In 1924, he took an appointment at the Friedrich-Wilhelms-Universität (today, the Humboldt-Universität zu Berlin) along with becoming a scientific member of the Kaiser-Wilhelm-Institut für physikalische Chemie und Elektrochemie (KWIPC, Kaiser Wilhelm Institute of Physical Chemistry and Electrochemistry) of the Kaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society).

[4] Ladenburg went to the United States as early as 1930,[5] where he became a Brackett Research Professor at the Palmer Physics Laboratory, Princeton University.

When the emigration wave from Germany began in April 1933, Ladenburg was the principal coordinator for the employment of exiled physicists in the United States.