Ernst Reissner (German: [ˈʁaɪsnɐ]; 24 September 1824 – 16 September 1878) was a Baltic German anatomist from Riga, Livonia. In 1851 he received his medical degree at the University of Dorpat (now known as the University of Tartu), and in 1855 became a professor of anatomy at Dorpat. In 1875, he retired from teaching for health reasons. Another anatomical structure that is named after him is Reissner's fiber, a long, fibrous aggregation of glycoproteins secreted by the subcommissural organ in the third ventricle and extending through the central canal of the spinal cord.