Harkon
From superman.nu: Supermanica
Harkon
A crazed scientist of Atlantis who performs experiments to give fish-like tails to Atlanteans born without them. To achieve his aim and help his daughter obtain a fish tail, Harkon uses red sun radiation to capture Superboy. Though temporarily transformed, Superboy is able to expose Harkon. However, after the scientist is killed, the Boy of Steel's memories of his adventure are removed by the residents of the undersea city (SB No. 194/1, Apr 1973: "The Super-Merman of the Sea!").
