Ilya Ilyich Mechnikov, also spelled Élie Metchnikoff, was a zoologist from the Russian Empire of Moldavian noble ancestry best known for his pioneering research in immunology and thanatology. He and Paul Ehrlich were jointly awarded the 1908 Nobel Prize in Physiology or Medicine "in recognition of their work on immunity".

Thanatology is the scientific study of death and the losses brought about as a result. It investigates the mechanisms and forensic aspects of death, such as bodily changes that accompany death and the postmortem period, as well as wider psychological and social aspects related to death. It is primarily an interdisciplinary study offered as a course of study at numerous colleges and universities.