Cassilis or Cassillis may refer to:
Cassillis House, a tower house near Maybole, Ayrshire, Scotland Cassilis, New Brunswick, a rural community in Northumberland County, New Brunswick, Canada Cassilis, New South Wales, a town in central-western New South Wales, Australia Cassilis, Victoria, a town in Gippsland, Victoria, Australia
See also Cassils (disambiguation) Earl of Cassilis, a title in the Peerage of Scotland