John Eyton Bickersteth Mayor (28 January 1825 – 1910) was an English classical scholar.
Mayor was born at Baddegama, Ceylon (now Sri Lanka). He went to England to be educated at Shrewsbury School and St John's College, Cambridge.
From 1863 to 1867 Mayor was librarian of the University of Cambridge, and in 1872 succeeded H. A. J. Munro in the professorship of Latin, which he held for 28 years. His best-known work, an edition of the thirteen Satires of Juvenal, is notable for an extraordinary wealth of illustrative quotations. His Bibliographical Clue to Latin Literature (1875), based on Emil Hübner's Grundriss zu Vorlesungen über die römische Litteraturgeschichte, was a valuable aid to the student, and his edition of Cicero's Second Philippic became widely used.
He also edited the English works of John Fisher, Bishop of Rochester (1876); Thomas Baker's History of St John's College, Cambridge (1869); Richard of Cirencester's Speculum historiale de gestis regum Angliae 447–1066 (1863–1869); Roger Ascham's Schoolmaster (new ed., 1883); the Latin Heptateuch (1889); and the Journal of Philology.
According to the Enciklopedio de Esperanto, Mayor learned Esperanto in 1907, and gave a historic speech against Esperanto reformists at the World Congress of Esperanto held at Cambridge.
His life and work are idiosyncratically and somewhat unsympathetically described in Juvenal's Mayor: The Professor Who Lived on 2d. a Day by J. G. W. Henderson.