David or Dave Callahan, Callaghan, or O'Callaghan may refer to:
David Callahan (fl. 1990s–2020s), founding editor of Inside Philanthropy, a digital media site Dave Callahan (1888–1969), American baseball player David Callahan (Home and Away), fictional character in the Australian soap opera Dave Callaghan (born 1965), South African cricketer Dave O'Callaghan (born 1990), Irish rugby union player David O'Callaghan (dual player) (born 1983), Irish hurler and former Gaelic footballer for Dublin David O'Callaghan (Kerry Gaelic footballer) (born 1987)
See also David Callaham (born 1977), American screenwriter and producer