William Munk (1816-1898) qualified as a physician in 1837 and practiced in London for more than 60 years. Munk became well known in the medical profession during the second half of the nineteenth century for his emphasis on the importance of narcotics for the relief of pain in incurable disease and was also a recognized authority on smallpox. In addition to his medical practice Munk was the Harveian Librarian of the Royal College of Physicians for almost 40 years and, among other biographical works, single-handedly produced the Roll of the Royal College of Physicians of London 1518-1700. His most significant clinical publication, Euthanasia, or Medical Treatment in Aid of an Easy Death, appeared toward the end of his career and was enthusiastically received by the medical and nursing professions. This paper gives a more detailed account of Munk's life and work than has yet appeared and focuses in particular on the contents and contemporary influence of his important late nineteenth century treatise on the care of the dying.