Hercules or Herkie was one of two giant frog-like robots (the other being Sampson) created by Dr. Dometone to guard the "Oceanic Plug" on Third Earth. He was nicknamed "Herkie" by Dr. Dometone. Hercules is green in color while Sampson is blue. Both the frogs sit atop the Oceanic Plug and guard it against any threat.
Hercules is an amphibious robot with the ability to travel both in water and on land. It moves about by walking and when standing upright on its two legs, it measures almost fifty feet in height. Its mouth is the main point of entry inside the robot. Hercules does not have any type of weapons, instead it relies on hand-to-hand combat using its strong hands to punch and pound any opponent. Hercules' eyes are two powerful lights which help the human controller inside to see better when the robot is in the dark depths of the oceans.