Reinhold Baer (22 July 1902 – 22 October 1979) was a German mathematician, known for his work in algebra.

Baer studied mechanical engineering for a year at Leibniz University Hannover.

Both of Baer's parents were Jewish, and he was for this reason informed that his services at Halle were no longer required.

Baer stayed at Princeton University and was a visiting scholar at the nearby Institute for Advanced Study from 1935 to 1937.

In 2016 the Reinhold Baer Prize for the best Ph.D. thesis in group theory was set up in his honour.