Based on the Shisa, a type of protective ward favoured in Japan, King Caesar is a colossal humanoid which has the traits of both lion and dog. It sports sharp teeth and claws, has what appears to be armour plating on its thighs and lower legs, and is capable of sustaining an enormous amount of physical punishment. In addition, some versions of King Caesar were capable of absorbing the energy attacks of its enemies and firing them back as concentrated power blasts.
When the Black Hole Planet 3 Aliens launched their first invasion of Earth using their giant robot MechaGodzilla, King Caesar was targeted as an obstacle to their goals. Whilst Caesar fought bravely, he was on the verge of defeat before Godzilla arrived, and the two were able to overcome and destroy their opponent and see off the attacking aliens.
Years later, King Caesar was one of Earth's monsters who fell under the control of the Xiliens and their mind-control device, being compelled to attack the island of Okinawa. The Xiliens later deployed Caesar, along with Rodan and Anguirus, in an attempt to stop Godzilla, who was threatening to put an end to their plans. However, Godzilla gained the upper hand, and threw Caesar into the other two, knocking all three unconscious.