Aaron Willard (October 14, 1757–May 20, 1844) was an entrepreneur, an industrialist, and a designer of clocks who worked extensively at his Roxbury, Massachusetts, factory during the early years of the United States of America. While at the family farm at Grafton, Aaron Willard developed his career conjointly with his three brothers, who became celebrated horologists too (though Aaron's and his brother Simon's creations are the most significant).