John William Fyfe (born 1839, date of death unknown) was a teaching physician in New York in the late nineteenth and early twentieth centuries. He was a physician of the Eclectic School and author of herbal manuals for physicians. His works include: The Essentials of Modern Materia Medica and Therapeutics also known as Fyfe's Materia Medica (1903), Pocket Essentials of Modern Materia Medica and Therapeutics (1911), and Specific Diagnosis and Specific Medication (1909).
On February 27, 1839, John William Fyfe was born in Swan's Island, Maine, a very small island town just off the coast of the mainland of Hancock County. Fyfe grew up and lived in Saugatuck, Connecticut—a small neighborhood within the city of Westport—for most of his life. He was the president of the Connecticut Eclectic State Medical Examination Board and an author of multiple works; one work that is noted is the Genealogy of the Family Fyfe.