Lewis Thomas (November 25, 1913 – December 3, 1993) was an American physician, poet, etymologist, essayist, administrator, educator, policy advisor, and researcher.

Thomas was born in Flushing, New York and attended Princeton University and Harvard Medical School. He became Dean of Yale Medical School and New York University School of Medicine, and President of Memorial Sloan-Kettering Institute. His formative years as an independent medical researcher were at Tulane University School of Medicine.

He was invited to write regular essays in the New England Journal of Medicine. One collection of those essays, The Lives of a Cell: Notes of a Biology Watcher (1974), won annual National Book Awards in two categories, Arts and Letters and The Sciences (both awards were split).

(He also won a Christopher Award for that book.) Two other collections of essays (originally published in NEJM and elsewhere) were The Medusa and the Snail and Late Night Thoughts on Listening to Mahler’s Ninth Symphony. In its first paperback edition, The Medusa and the Snail won another National Book Award in Science.His autobiography, The Youngest Science: Notes of a Medicine Watcher, is a record of a century of medicine and the changes which occurred in it. He also published a book on etymology titled Et Cetera, Et Cetera, poems, and numerous scientific papers.

Many of his essays discuss relationships among ideas or concepts using etymology as a starting point. Others concern the cultural implications of scientific discoveries and the growing awareness of ecology. In his essay on Mahler’s Ninth Symphony, Thomas addresses the anxieties produced by the development of nuclear weapons. Thomas is often quoted, given his notably eclectic interests and superlative prose style.

The Lewis Thomas Prize is awarded annually by The Rockefeller University to a scientist for artistic achievement.