Constantin Brunner (1862–1937) was the pen-name of the German Jewish philosopher Arjeh Yehuda Wertheimer (called Leo). He was born in Altona (near Hamburg) on 27 August 1862. He came from a prominent Jewish family that had lived in the vicinity of Hamburg for generations; his grandfather, Akiba Wertheimer, was chief Rabbi of Altona and Schleswig-Holstein. Brunner studied philosophy under a number of prominent scholars, but never completed his doctorate.