Halladay is an English and Scottish surname which may refer to:
Daniel Halladay (1826–1916), American engineer, inventor and businessman Howard Hadden Halladay (1876–1952), Canadian politician Roy Halladay (1977–2017), American baseball player
See also Halladay (automobile), a defunct American automobile manufacturing company founded in 1905 Halladay Farmhouse, Duanesburg, New York, on the National Register of Historic Places Halliday, a list of people with the surname Halliday or Haliday