John Edgar (ca. 1750–1832) was an Illinois pioneer and politician. He was born in Ireland. In 1776, he was the commander of a British ship in the Great Lakes. He resigned from the British Navy rather than fight against the Americans. Edgar settled at Fort Kaskaskia in 1784. He became a merchant, and built a flour mill. He shipped large quantities of flour from Illinois to New Orleans. Edgar was an Illinois delegate to the Legislature of the Northwest Territory. He also served as Justice of the Peace and Judge in Kaskaskia.