Emerich Ullmann (February 23, 1861 – 1937) was an Austrian surgeon who was a native of Pécs.
In 1884 he received his doctorate in Vienna, and afterwards worked in the surgical department of Theodor Billroth (1829–1894). He briefly was an assistant to Louis Pasteur (1822–1895) in Paris, where he was involved with research of antisera against rabies. In 1885 he returned to the University of Vienna at the First Department of Surgery.
Ullmann was a pioneer concerning renal transplantation. In 1902 he performed the first successful renal autotransplantation in a dog. Reportedly, the kidney remained functional for five days. Soon afterwards, he was unsuccessful in trying the first renal xenotransplantation (cross-species transplant) between a goat and a dog. Following an unsuccessful attempt to transplant a pig's kidney into a human patient who was in the final stage of renal disease, he stopped research of kidney transplantation. Ullmann also conducted research involving tissue and other organ transplants.