John Nash Douglas Bush (1896–1983) was a literary critic and literary historian. He taught for most of his life at Harvard University, where his students included many of the most prominent scholars, writers, and academics of several generations, including Walter Jackson Bate, Neil Rudenstine, Paul Auster and Aharon Lichtenstein. Students from the 60's report that Bush would sometimes speak in decasyllables, so that it was hard to tell where his recitation of Milton left off and where his commentary began.
Bush's textual criticism on Shakespeare and John Milton was widely influential. His English Literature in the Earlier Seventeenth Century remains a standard reference work.