Godzilla (Main Theme)

Godzilla (Main Theme) is a musical main theme written for the 1954 film "Godzilla". Originally intended to be associated with the Japanese Self Defense Forces featured in the film, it became the official theme song for the monster character Godzilla and the entire franchise.
Despite the track being titled as "Main Title" on the "Godzilla" soundtrack, fans and Toho executives know the track as the "Main Godzilla Theme" or the "Godzilla (Main Theme)" song.
The song first appeared on the original "Godzilla" film and in later sequels was replaced by a new theme titled the "Godzilla March".
The "Godzilla (Main Theme)" was re-used for the first time in "Terror of Mechagodzilla", the final Godzilla film featuring the Showa era's continuity within the franchise.
Alterations.
As the theme song was brought back in sequels, it was also altered to fit in with the tone of the film. When it was brought back in "Terror of Mechagodzilla", the main title from the film was mixed with the theme song. 
The only two songs on the "Terror of Mechagodzilla" soundtrack that have the "Godzilla Theme" mixed with the main titles are "The Appearance of Godzilla", "Godzilla vs. The Mega-Monster Tag-Team", and the "Main Title" itself.
On the "Godzilla vs. Biollante and Godzilla vs. King Ghidorah Soundtrack", the tracks "Begin The Attack!" and "Godzilla vs. King Ghidorah" are actually the "Godzilla Theme", but they are not altered in any way.
On the "Godzilla vs. King Ghidorah Soundtrack", the track "Godzilla's Resurrection" is a mixture of the "Godzilla Theme" and the "Godzilla March", the second official Godzilla theme.
The ending title track from "Godzilla vs. Destoroyah" is the "Godzilla Theme" song with mixed excerpts from the "King Kong vs. Godzilla" soundtrack.
Keith Emerson arranged the track for the "" soundtrack, keeping the track titled as "Godzilla (Main Theme)".
Bear McCreary arranged the track for the "" soundtrack, keeping the track titled as "Godzilla Main Title" in addition to using it throughout the film as a theme for the titular character.