Dr. Jelke learned the secret of transforming himself into a monster from reading Robert Louis Stevenson's novel, The Strange Case of Dr Jekyll and Mr Hyde. After a short series of brutal murders and two encounters with Mister Scarlet, Mr. Hyde got involuntarily transformed back into Dr. Jelke, by a blow to the head. Jelke grabbed a flask of some chemical concoction, gulped it down, and dropped dead.
- Mental Illness Jelke had a split personality, the side-effect of his becoming the monstrous Mr. Hyde.
- This version of Mister Hyde, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- Apparent Death: Jelke was a doctor, who concocted his own potions, and he drank one of them, seemingly dying by his own hand. Nobody but Jelke knew what was really in that test tube.
- 1 Appearances of Jelke (Earth-S)
- 2 Images featuring Jelke (Earth-S)
- Quotations by or about Jelke (Earth-S)
- Character Gallery: Jelke (Earth-S)