Alexander Fiedemann, born Reuben Pesachovich Fidelman, was a Russian-German virtuoso violinist and music teacher. He was born on 25 October 1878 in Kyiv. At the age of six he received his first violin lessons from his father, a klezmer musician, and made his public debut in Kyiv at eight.
From 1887 to 1891, he studied with Otakar Ševčík at the Kyiv School of the Imperial Russian Musical Society, then continued at the Leipzig Conservatory with Adolf Brodsky. Between 1891 and 1895, he toured America with Brodsky and appeared at Carnegie Hall at the age of thirteen. During this period he effectively lived with the Brodsky family, who regarded him as a pupil whose musical education they wished to complete.
After returning to the Russian Empire, Fidelman taught at the Odessa Music School of the Imperial Russian Musical Society from 1897 to 1907 and performed as a soloist. His pupils there included Mischa Elman, Naoum Blinder, Nikolai Moldavan, and Alexander Shaikhet. He also led the string quartet of the Odessa branch of the society before Jaroslav Kocian succeeded him as first violinist.
In 1907 he moved to Berlin and adopted the surname Fiedemann. With assistance from his former pupil Mischa Elman, he joined the Stern Conservatory, where he taught from 1908 to 1919. His Berlin pupils included Toscha Seidel, Boris Kroyt, and Raphael Hillyer, and he also directed a string quartet in which Kroyt soon played viola. Critics praised his virtuosity; a 1918 review described him as one of the leading living violinists.
Fiedemann married Fanny Ruden in Berlin in 1927. They later lived in Prague, where he died on 28 January 1940 and was buried in the New Jewish Cemetery. An obituary in the Prague Jewish newspaper Jüdisches Nachrichtenblatt remembered him as Brodsky's beloved pupil, the teacher of Elman and Seidel, leader of one of the world's finest quartets, and a distinguished musician.