Gabriel Anton Walter was a builder of pianos. The Grove Dictionary of Music and Musicians describes him as "the most famous Viennese piano maker of his time".
Anton Walter. Oil painting by Friedrich Gauermann, 1825 (Vienna, Kunsthistorisches Museum)
Fortepiano by Anton Walter & Sohn (Vienna, ca. 1805) – Berlin, Musikinstrumentenmuseum
Fortepiano by Paul McNulty, based on a historical instrument by Walter & Sohn, 1805
Johann (Georg) Andreas Stein was an outstanding German maker of keyboard instruments, a central figure in the history of the piano.
Piano purportedly by Johann Andreas Stein (Augsburg, 1775) - Berlin, Musikinstrumentenmuseum, but probably by Louis Dulcken in imitation of Stein's work