The Invisible Man - Dr. Gade

The Invisible Man Mystic Comics #2 - 4 (April 1940 – August 1940)
In one of those freak scientific miracles that were so common in the pulp fiction of the 1940's and 50's, brilliant young scientist, Dr. Gade survives being burned to death after been thrown into a blast furnace when the chemicals accidentally spilled on him by his would-be assassin render him impervious to fire. As an added benefit, Gade discovers that, in combination with the rays from a special machine in his lab, the chemicals allow him to become invisible or visible at will. So empowered, Dr. Gade hunts down and kills the men behind the attempt on his life. He throws one out of a window on the 40th floor of an office tower, shoots another and blasts a third, the "unscrupulous money king" behind the whole affair, into atoms with a disintegrator ray.
The body count in the Invisible Man's war on crime continued to mount in his subsequent exploits, before the good doctor vanished for good after his third adventure in Mystic Comics # 4.