John Bon and Mast Parson is a literary work printed in 1547 or 1548 by John Day and William Seres as the work of "Lucas Shepeherd", possibly a pseudonym. John Bale uses the alternative names 'Lucas Opilio' and 'Lucas Shepeherd' for the author, who was probably a poet and physician from Colchester in Essex, a friend of Edward Underhill and the author of eight anti-Catholic verse satires (mostly in tetrameter) and one prose satire in the time of King Edward VI. His work attacks the mass, transubstantiation, the feast of Corpus Christi, the Roman Catholic clergy and doctrine, and clerical celibacy. Bishop Stephen Gardiner, William Layton, and Dr Richard Smith are specifically targeted.