The year 2016 marks 100 years since the death of Élie Metchnikoff (1845-1916), the Russian zoologist who pioneered the study of cellular immunology and who is widely credited with the discovery of phagocytosis, for which he was jointly awarded the Nobel Prize in Physiology or Medicine in 1908. However, his long scientific career spanned many disciplines and has had far-reaching effects on modern immunology beyond the study of phagocytosis. In this Viewpoint article, five leading immunologists from the fields of phagocytosis, macrophage biology, leukocyte migration, the microbiota and intravital imaging tell Nature Reviews Immunology how Metchnikoff's work has influenced past, present and future research in their respective fields.