Alexander Altmann (April 16, 1906 – June 6, 1987) was an Orthodox Jewish scholar and rabbi born in Kassa, Austria-Hungary (present-day Košice, Slovakia). He emigrated to England in 1938 and later settled in the United States, working productively for a decade and a half as a professor within the Philosophy Department at Brandeis University. He is best known for his studies of the thought of Moses Mendelssohn, and was indeed the leading Mendelssohn scholar since the time of Mendelssohn himself. He also made important contributions to the study of Jewish mysticism, and for a large part of his career he was the only scholar in the United States working on this subject in a purely academic setting. Among the many Brandeis students whose work he supervised in this area were Elliot Wolfson, Arthur Green, Heidi Ravven, Paul Mendes-Flohr, Lawrence Fine, and Daniel Matt.