Jonathan I Rashleigh (4 July 1591 – 1 May 1675), of Menabilly, near Fowey in Cornwall, was an English shipping-merchant, Member of Parliament for Fowey in 1614, 1621, 1625, April 1640 and November 1640, and 1661 and served as Sheriff of Cornwall in 1627. He supported the Royalist cause during the Civil War.