Nikobo is a hippopotamus who became a bodyguard to Prince Tazander Tazah of Ozamaland, during his exile on Patrippany Island, and later joined the Crescent Moon's mission to restore him to his throne. (Captain Salt in Oz)
Other works
Nikobo appears in Marcus Mebes' series The Royal Explorers of Oz.
Background
The name Nikobo is remarkably similar to Nikobob, a male human from L. Frank Baum's Rinkitink in Oz.
Nikobo in The Royal Explorers of Oz
In Who's Who in Oz, Jack Snow misgenders Nikobo as male.