Metchnikoff, Élie (Russian: Ilya Ilich Mechnikov)(1845-1916), a Russian-French biologist. In 1884 Metchnikoff discovered that certain white blood cells, which he called phagocytes, engulf and digest bacteria. He called these cells the body's first line of defense against disease. Metchnikoff and Paul Ehrlich shared the 1908 Nobel Prize in physiology or medicine for work in immunology.

Metchnikoff was born in Ukraine. He attended the universities of Kharkov, Giessen, Göttingen, and Munich. He taught at the University of Odessa, 1870-82. In 1888, at the invitation of Louis Pasteur, Metchnikoff joined the Pasteur Institute in Paris, becoming a subdirector in 1904.