William Findley (c. 1741 – April 4, 1821) was an Irish-born farmer and politician from Westmoreland County, Pennsylvania. He served in both houses of the state legislature and represented Pennsylvania in the U.S. House from 1791 until 1799 and from 1803 to 1817. By the end of his career, he was the longest serving member of the House, and was the first to hold the honorary title "Father of the House".