Charles Foster Tillinghast Sr. (September 18, 1871 – October 3, 1948) was a business executive, yachtsman and a National Guard officer who held the rank of colonel during World War I.
He was named after his grandfather Charles Foster Tillinghast (1797–1864) and was a descendant of Rhode Island colonial governor Stephen Hopkins who was a signer of the Declaration of Independence.
After graduation, he was employed by the Textile-Finishing Machinery Company of Providence from which he retired in 1941 as vice president and managing director.
On May 20, 1898, he volunteered for active duty as a captain and served as commander of Company A of the 1st Rhode Island Infantry during the Spanish–American War.
He was elected as the lieutenant colonel for the Rhode Island Coast Artillery District on October 20, 1908.