Daykin is a surname. Notable people with the surname include:
Bert Daykin, Australian rules footballer Christopher Daykin, British actuary Percy Daykin, Australian rules footballer Richard Daykin, Australian rules footballer Thomas Daykin, English footballer Tony Daykin, American football player
See also Daykin, Nebraska, a village in Jefferson County Ahlswede–Daykin inequality, an inequality in statistical mechanics Alexander and Daykin, Millette Alexander and Frank Daykin, an American piano duo