John Henry Clarke (1853 – 24 November 1931) was an English classical homeopath, and one of the highest-profile antisemite of his era in Great Britain.

[2] As a physician Clarke had a clinic in Piccadilly, London, which was quite successful, and had many private clients.

He was the chair at the meeting where The Britons was founded, as an associate of Henry Hamilton Beamish, and was vice-president and chairman until his death.

[4] Clarke criticized the germ theory of disease and experiments of Louis Pasteur.

[6] He wrote many books, his best known were Dictionary of Practical Materia Medica and Repertory of Materia Medica (i.e., the Clinical Repertory), both of which are recommended by the U.S. Food and Drug Administration's rules on "Conditions under Which Homeopathic Drugs May be Marketed".