John Robin Warren AC (born 11 June 1937 in Adelaide) is an Australian pathologist, Nobel Laureate and researcher who is credited with the 1979 re-discovery of the bacterium Helicobacter pylori, together with Barry Marshall.
He received his MBBS degree from the University of Adelaide, having completed his high school education at St Peter's College, Adelaide. In 1967 he was admitted into the Royal College of Pathologists of Australasia and became a senior pathologist at the Royal Perth Hospital where he spent the majority of his career. At the University of Western Australia with his colleague Barry J. Marshall, Warren proved that the bacterium is the cause of stomach ulcers. Warren helped develop a convenient diagnostic test (14C-urea breath-test) for detecting H. pylori in ulcer patients. In 2005, Warren and Marshall were awarded the Nobel Prize in Medicine.
He married Winifred Theresa Warren (née Williams) and together they had six children. Winifred Warren went on to become an accomplished psychiatrist.
An Australian documentary was made in 2006 about Warren and Marshall's road to the Nobel Prize, called "The Winner's Guide to the Nobel Prize". He was appointed a Companion of the Order of Australia in 2007.