Alois Alzheimer  (1864-1915)
German professor of psychology

In 1906 Alzheimer gave a lecture in which he identified an 'unusual disease of the cerebral cortex' which affected a woman in her fifties, causing memory loss, disorientation, hallucinations and ultimately her death at only 55. Emil Kraepelin, the head of the lab at the University of Munich Medical School where Alzheimer worked at the time, named the disease Alzheimer's.  

Adapted from www.alz.co.uk/alzheimers/aa.html