Badmannah the Terrible is a giant who terrorizes the land by scooping up people and treasures with his magical fishnet. Finally the denizens of Whackajammy, sick of his antics, band together to defeat him, sending him to the bottom of the Nonestic Ocean.
Badmannah bears a striking resemblance to Rhynn. Both are giants who carry large fishing nets. While Badmannah seeks out treasure, Rhynn seeks his lost eye. They each also catch a supporting character in their respective stories.
Rhyn appeared first in The Knight of Swords in 1971, just one year before Yankee in Oz was published. However, Thompson apparently wrote Yankee in 1959.