The Chincoteague Pony, also known as the Assateague horse, is a breed of pony that developed and lives in a feral condition on Assateague Island in the United States states of Virginia and Maryland. The breed was made famous by the Misty of Chincoteague series written by Marguerite Henry starting in 1947. While phenotypically horse-like, they are commonly called "ponies". This is due in part to their smaller stature, created by the poor habitat present on Assateague Island. Island Chincoteagues live on a diet of salt marsh plants and brush. Although popularly known as Chincoteague ponies, the feral ponies actually live on Assateague Island.
Several legends are told regarding their origins, the most likely that they descend from stock released on the island by colonists looking to escape livestock laws and taxes on the mainland. In 1835, the practice of pony penning began, rounding up ponies and removing some of them to the mainland. In 1924 the first official "Pony Penning Day" was held by the Chincoteague Volunteer Fire Company, where ponies were auctioned as a way to raise money for fire equipment, an annual event that continues to the present day.