Peter Heylyn or Heylin (29 November 1599 – 8 May 1662) was an English ecclesiastic and author of many polemical, historical, political and theological tracts.

At the Restoration, he left Abingdon and was made sub-Dean of Westminster, but poor health prevented further advancement.

Among his works are a History of the Reformation of the Church of England, and a Life of Archbishop William Laud (Cyprianus Anglicanus) (1668).

He affixed Greek titles to two of his books, Κειμήλια Ἐκκλησιαστικά: Historical and miscellaneous tracts (1662) and Ἡρωολογία Anglorum; or, a help to English history (1641).

[7] He was the writer of the "Cosmographie", an attempt to describe in meticulous detail every aspect of the known world in 1652, the geography, climate, customs, achievements, politics, and belief systems.

It appears to have been the first description in print of Australia, and perhaps of California, Terra del Fuego, and other territories in the New World.

He objected to the name "America" as it placed undue glory on Amerigo Vespucci, and recommended "Columbana" or "Cabotia" as more indicative of the true discoverers, Columbus and Cabot.