Robert McMillan may refer to:
Robert S. McMillan (architect) (1916–2001), architect and co-founder of The Architects Collaborative Robert S. McMillan (astronomer) (born 1950), astronomer at the University of Arizona Robert McMillan (Australian judge) (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 (born 1952), Canadian hockey player and politician Robert Macmillan (1921–2015), British mechanical engineer
See also Robbie Coltrane (actually Anthony Robert McMillan, 1950–2022), Scottish actor McMillan (surname)