Man Made Monster (1941)

"Big Dan" McCormick is the sole survivor of a bus crash into hydro lines. 5 others were electrocuted. Intrigued by Dan's apparent immunity to electricity, Dr. John Lawrence, distinguished elector-biologist, asks Dan to visit him at his laboratory, where Lawrence's assistant, Dr. Paul Rigas, is secretly conducting experiments to prove his theory that human life can be motivated and controlled by electricity. Rigas persuades Dan to submit to tests, where Dan absorbs increasingly powerful charges until he develops an amazing degree of immunity, and becomes a walking hulk of electricity. Rigas does a final test of pouring a tremendous charge into Dan's body, and Dan becomes superhuman and his body glows. He is also a robot that is controlled by Rigas. When Lawrence tries to stop the experiment, Rigas orders Dan to kill him. Rigas removes the electricity from Dan's body and he becomes a shrunken shell. Despite the efforts of June Meredith, Lawrence's niece, and newspaper reporter Mark Adams to help him, Dan is sentenced to die in the electric chair. But in the death-chamber he absorbs three shocks which returns him to superhuman status. He escapes and goes after Rigas, after putting on a rubber suit to encase his electric energy.