Mothra vs. Godzilla (1964)
Mothra vs. Godzilla is a 1964 Japanese science fiction kaiju film produced by Toho. Directed by IshirÅ Honda, and featuring special effects by Eiji Tsuburaya, the film starred Akira Takarada, Kenji Sahara and Hiroshi Koizumi. The fourth film in the Godzilla series, it was the first in which Toho began bringing in monsters from other productions, having Godzilla cross paths with Mothra. This trend would continue later in the same year with Rodan, in the film Ghidorah the Three Headed Monster.
More at Wikipedia.