Milletaire made his film debut with a bit part in the 1947 film A Double Life which starred Ronald Colman.
Milletaire had bit parts in the classic films Naked City, Singin' in the Rain, and North by Northwest.
In Milletaire's first appearance on The Untouchables he played an IRS agent. In four subsequent appearances, he would play a gangster.
The last name of Milletaire's character on The Untouchables was changed from Nick Tomassi to Pete Konitz in order to appease Italian-American groups protesting the show's use of Italian surnames for its villains.
Milletaire's trademarks were his hard, cruel face and his icy gaze.