The Invisible Ray is a 1936 American science-fiction horror film directed by Lambert Hillyer. It stars Boris Karloff as Dr. Janos Rukh, a scientist who comes in contact with a meteorite composed of an element known as "Radium X". After exposure to its rays begins to make him glow in the dark, his touch becomes deadly, and he begins to be slowly driven mad. Alongside Karloff, the film's cast includes Bela Lugosi, Frances Drake, Frank Lawton, Walter Kingsford, Beulah Bondi, Violet Kemble Cooper, and Nydia Westman.

Prior to production, Universal Pictures was originally developing the film Bluebeard for Karloff and Lugosi. When that production did not start, Universal wanted a release by the end of 1935 with Karloff and Lugosi, and hired director Stuart Walker and screenwriter John Colton to make the film The Invisible Ray. As Walker was dissatisfied with Colton's script, he requested a three-day delay before production was set to begin and after being denied this, he left the production and was replaced with Lambert Hillyer. Hillyer began and completed the film over-budget and over the originally set production time.