Karl Thiersch, also spelled Carl Thiersch (April 20, 1822 – April 28, 1895), was a German surgeon who was born in Munich. He received his doctorate from the University of Munich in 1843 and later became a professor of surgery at the universities of Erlangen (1854) and Leipzig (1867). He was a medical surgeon during the First War of Schleswig and a medical consultant in the Franco-Prussian War. His father was educationist Friedrich Thiersch, his father-in-law was renowned chemist Justus von Liebig. One brother, Ludwig, was an influential painter, while another, H.W.J., was a theologian.
Thiersch made several contributions in medicine. He was the first to demonstrate that epithelial cancer metastasizes through the spread of malignant cells. He modified Joseph Lister's technique of antiseptic sterilization by substituting salicylic acid for carbolic acid. Also, Thiersch's graft is a method of split-skin grafting that he created. This graft is also referred to as a Ollier-Thiersch graft; named along with French surgeon Louis Léopold Ollier (1830-1900).