Ilya Ilyich Mechnikov (16 May 1845 – 16 July 1916) was a Ukrainian zoologist of (partly) Jewish descent (his mother was Jewish). He won the 1908 Nobel Prize in Physiology or Medicine, with Paul Ehrlich, for finding out how immunity fights disease.
Mechnikov was a protozoologist who became better known for the discovery of macrophages in 1882. He discovered how they dealt with germs by phagocytosis. Macrophages are found in virtually all tissues, and patrol for potential pathogens by amoeboid movement.
He is also credited with coining the term gerontology in 1903, for the emerging study of ageing and longevity.
He was born in Kharkov (now Kharkiv), Russian Empire (now Ukraine)