Mogu

History:
Mogu was a short lived creation, he was intended to take Megalon's place in the 1972 version of The Return of King Ghidorah after it was adapted from Godzilla vs. the Space Monsters. However that script fell through also, and Mogu has not been even considered for a script since. Not much is known about Mogu, except that he has the ability to fly and fire some kind of projectile from his mouth.

Note, no picture of Mogu exists beyond a concept art drawing for the script. The above picture of him is the Toho Kingdom's interpretation of the concept art, using it as a model and then fleshing it out.