Robert Middlemass (3 September 1883, New Britain, Connecticut – 10 September 1949, Los Angeles, California) was an American playwright and stage actor, and later character actor with over 100 film appearances. usually playing detectives or policemen.

Middlemass graduated from Harvard University in 1909 and initially went into the insurance business, but soon went on the stage, joining the Castle Square Theatre stock company in Boston. He debuted on Broadway in September 1914 in The Bludgeon at the Maxine Elliott Theatre.