Karl Heinrich Barth (July 12, 1847 – December 23, 1922) was a noted German pianist and pedagogue.
He was born in Pillau, East Prussia (now Baltiysk, Russia). His teachers included Hans von Bülow, Hans von Bronsart and Carl Tausig. All three were leading musicians of the era and had close associations with Franz Liszt. Barth's first major position was as a professor of piano at the Stern Conservatory in Berlin, where he also served as court pianist to Crown Prince Friedrich, later Kaiser Friedrich III of Prussia. In 1868, Barth took a position in London teaching piano at the Royal Academy of Music. From 1910 until his death, he taught at the Berlin Hochschule für Musik, where his pupils included Arthur Rubinstein, Wilhelm Kempff and Rose and Ottilie Sutro.
He frequently performed in public with the violinist, conductor and composer Joseph Joachim and with Joachim's wife, the singer Amalie Weiss. He also formed a piano trio with the violinist Heinrich Karl Hermann de Ahna and the cellist Robert Hausmann. The trio was well known and widely celebrated.
He died in Berlin in December 1922.