Christian Albert Theodor Billroth (26 April 1829 – 6 February 1894) was a Prussian-born Austrian surgeon and amateur musician.As a surgeon, he is generally regarded as the founding father of modern abdominal surgery. As a musician, he was a close friend and confidant of Johannes Brahms, a leading patron of the Viennese musical scene, and one of the first to attempt a scientific analysis of musicality.