Godzilla Vs. Mechagodzilla aka Godzilla Vs. the Bionic Monster aka Godzilla Vs. the Cosmic Monster

For Godzilla's 20th anniversary Toho wanted a new opponent, something he had not faced before. Remembering they had Kong face a robot duplicate, they decided to have Godzilla face his own mechanical doppelgänger. Also made the aliens controlling Mechagodzilla, in honor of King Kong, are apes, or maybe it was because of the popularity of the Planet of the Apes movies.