Carl Heitzmann (2 October 1836 – 6 December 1896) was an Austrian pathologist and dermatologist.
Heitzmann was born in Vinkovci (then Syrmia/Szerém/Srijem, Slavonia, Kingdom of Hungary, today Croatia) and studied medicine in Budapest and Vienna, earning his doctorate in 1859. After graduation he furthered his studies in Vienna under Franz Schuh (1804 - 1864), Ferdinand Hebra (1816 - 1880), Salomon Stricker (1834 - 1898), and Carl Rokitansky (1804 - 1878). When he was unable to succeed Rokitansky as the chair of pathology at Vienna, he emigrated to New York in 1874, where he was one of the founders of the American Dermatological Association (ADA).
Heitzmann is credited for being the first physician to describe the precursor corpuscles of red cells, which he referred to as hematoblasts. In 1872 he documented his findings in a treatise titled Studien am Knochen und Knorpel, where he mentions that his discovery of the hematoblast was in the bone marrow of an injured dog's leg.
Heitzmann was a skilled illustrator and lithographer, and renowned for his work with water colors. Among his artistic works are water color illustrations he created with Anton Elfinger (1821 - 1864) in Hebra's 1876 Atlas der Hautkrankheiten (Atlas of Skin Diseases). Among Heitzmann's written works was the popular Compendium der chirurgischen Pathologie und Therapie (Compendium of Surgical Pathology and Therapy, two volumes- 1864 & 1868).