John Leyburn (1615 – 20 June, 1702) was an English Roman Catholic bishop who served as the Vicar Apostolic of England from 1685 to 1688 and then when it was divided served as the Vicar Apostolic of the London District from 1688 to 1702. He was not only a theologian, but also a mathematician, and an intimate friend of Descartes and Hobbes.