Robert McMillan may refer to:Robert S. McMillan (architect) (1916–2001), architect and co-founder of The Architects Collaborative Robert S. McMillan (astronomer), astronomer at the University of Arizona Robert McMillan (1858–1931), Chief Justice of the Supreme Court of Western Australia Robert Johnston McMillan (1885–1941), U.S. federal judge Robert McMillan (farmer) (1887–1962), member of the New Zealand Legislative Council Robert McMillan (footballer) (1857–1928), Welsh footballer Robert MacMillan (1865–1936), Scottish national rugby union player Bob MacMillan, Canadian hockey player and politician