Robert Arthur (born Robert Paul Arthaud; June 18, 1925 – October 1, 2008) was an American motion picture actor who appeared in dozens of films in the 1940s and 1950s. He appeared in the 1949 war film Twelve O'Clock High as the comic relief–providing Sgt. McIllhenny, in the 1951 Billy Wilder film Ace in the Hole, and in the 1950s television program The Lone Ranger. Arthur was known for playing youthful teenage or young adult roles.

In his later years, Arthur became an activist for gay rights on behalf of senior citizens. He died in Aberdeen, Washington in 2008, aged 83.