The Man They Could Not Hang is a 1939 American horror film directed by Nick Grinde from a screenplay by Karl Brown. It stars Boris Karloff as Dr. Henryk Savaard, a scientist who develops a procedure for bringing the dead back to life. When he is arrested and sentenced to be executed for murdering a young medical student who volunteered to be killed to test the procedure, Savaard vows retribution on the individuals responsible. Alongside Karloff, the film's cast includes Lorna Gray, Robert Wilcox, and Roger Pryor.

William Henry Pratt, known professionally as Boris Karloff and occasionally billed as Karloff the Uncanny, was an English actor. His portrayal of Frankenstein's monster in the horror film Frankenstein (1931) established him as a horror icon, and he reprised the role for the sequels Bride of Frankenstein (1935) and Son of Frankenstein (1939). He also appeared as Imhotep in The Mummy (1932), and voiced the Grinch in, as well as narrating, the animated television special of Dr. Seuss' How the Grinch Stole Christmas! (1966), which won him a Grammy Award.