Sir Walter Massy-Greene KCMG (6 November 1874 – 16 November 1952) was an Australian politician and businessman. As a Liberal and Nationalist member of the House of Representatives, he became a protégé of Prime Minister Billy Hughes and was groomed as his successor. He served as Minister for Trade and Customs (1919–1921), Defence (1921–1923), and Health (1921–1923), but his prime ministerial aspirations were brought to an abrupt halt by his defeat at the 1922 federal election. Massy-Greene subsequently served two terms as a Senator for New South Wales (1923–1925, 1926–1938), but never regained his earlier influence in politics. In retirement he held numerous company directorships.