Mer-Boy was a young merman who harbored a romantic interest in the Amazon adventurer, Diana when they were teenagers. When Mer-Boy grew up, he took the name Mer-Man and reunited with Diana, who was now operating under the guise of Wonder Woman.
- Having no legs, Mer-Boy has difficulty operating outside of the water. When on land he can only move about by awkwardly hopping on his tail fin.
- This version of Ronno (Earth-One), 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.
- As a teenager, Mer-Boy's true name was Ronno. As an adult, he took the name Manno. The purpose behind this name change has never been explained.
- 22 Appearances of Ronno (Earth-One)
- 1 Images featuring Ronno (Earth-One)
- 1 Quotations by or about Ronno (Earth-One)
- Character Gallery: Ronno (Earth-One)