Louis Brassin (24 June 1836 – 5 May 1884) was a Belgian pianist, composer and music teacher, described as the finest Belgian pianist of his era. He was born in Aachen into the family of an opera singer and was the great-nephew of the noted flautist Louis Drouet.
In 1847, the Brassin family moved to Leipzig after his father received an opera engagement there. Louis studied at the Leipzig Conservatory with Ignaz Moscheles and began giving concerts as a child. He later performed with his younger brothers, the pianist Leopold Brassin and the violinist Gerhard Brassin, and also appeared with the string quartet led by Jacques Dupuy.
Brassin composed two short operas, two piano concertos, and a range of piano pieces and arrangements. His arrangements of five excerpts from Richard Wagner's tetralogy The Ring of the Nibelung were particularly well known.
He began teaching in 1866 at the Stern Conservatory in Berlin. From 1868 to 1878 he was a professor at the Brussels Conservatory, where his students included James Kwast, Edgar Tinel and Isaac Albéniz. In 1878 he joined the St. Petersburg Conservatory, teaching there until his death; his pupils included Albert Bensch, Vasily Safonov and Vasily Sapelnikov.