John Hearle Tremayne (17 March 1780 – 27 August 1851) was a member of a landed family in the English county of Cornwall, and owner of the Heligan estate near Mevagissey. He was a member of the UK Parliament for the constituency of Cornwall, a Justice of the peace, and High Sheriff of Cornwall in 1831. He was also the second of four successive members of the Tremayne family who are credited with the creation of the gardens around Heligan House that are now well known as the Lost Gardens of Heligan.