Charles Frederick "Boots" Day (born August 31, 1947) is an American former professional baseball outfielder.
A native of Ilion, New York, Day played Major League Baseball for all or parts of six seasons (1969–74), with the bulk of that time spent with the Montreal Expos.
He threw and batted left-handed, stood 5 feet 9 inches (1.75 m) tall and weighed 160 pounds (73 kg).
In recent years he had served as hitting coach with the Evansville Otters of the independent Frontier League.