- Japanese title (1965): Kaijū Daisensō (Great Monster War)
- Toho’s English title (promotional): Invasion of Astro-Monster*
- American “working title” (circa 1966): Invasion of the Astro-Monsters**
- American release title (1970): Monster Zero
- Alternate American release title (1967?-197X?): Invasion of the Astros***
- Toho Champion Festival release title (1971-1986): Kaijū Daisensō: Kingu Gidora tai Gojira (Great Monster War: King Ghidorah vs. Godzilla)****
- American video/TV title (1980?-circa 2006): Godzilla vs. Monster Zero*****
*Promotional materials with this title include a trailer, posters, and lobby cards. I’m sure press books and other traditional advertisements were made as well, I just haven’t seen them. There’s no evidence that any print with this title was ever struck. This is the title Toho wants distributors to use today, so that's why the Classic Media DVD and the Filmstruck versions were presented with this title. I hate hate hate that the subtitles for the Japanese versions of those releases translate 『怪獣大戦争』 as "Invasion of Astro-Monster" because that's totally dishonest, but that's the title Toho wants on their movie so these distributors have no choice but to cooperate.
**Reported in Variety
circa 1967 (don’t have Steve Ryfle’s book in front of me but I believe that’s mentioned in his text). Saperstein wasn’t able to release the film in the U.S. until 1970, as “Monster Zero.” There is
a print with this “working title” in Toho’s possession. It’s sometimes referred to as an “international version” but there’s a long and technical explanation to why that version (released on video in the U.K.) is neither the original American nor an original Toho international version. Whew.
***Posters exist for this version, supposedly available for overseas military bases to exhibit. It was also supposedly available in 16mm rental catalogs at one point. Not much is known about this, and the only photo of the title is in black and white (maybe a rental print, since printing on monochrome stock would have been cheaper). This might have been another “working title” of which prints were later struck and repurposed for the film rental market.
****This version was also heavily edited for the Champion Festival, and this edited release was the only Japanese version available until Toho released the full length original theatrical release on video & Laserdisc in 1986. (The initial 1983 Toho Video release was this 75 minute Matsuri version.)
****When Saperstein/UPA prepared new versions of his five Godzilla films for TV and video in the early ‘80s he took the opportunity to retitle this film (probably to make it clear it was a Godzilla film), “Godzilla vs. The Thing” (as “Godzilla vs. Mothra”, probably to make it clear that
was a Mothra movie) and TOMG (which I won’t get into here, it’s too confusing). Anyway, this version is essentially the original U.S. release with a new title. Released on video by Paramount (83, 89, 94), Simitar (98), and on Laserdisc in ‘94. Heavily syndicated on television, usually seen on the Turner networks and AMC. I think the last time this version was seen on television was in 2006 on AMC.
“Monster Zero” was first released on video by Simitar (unlicensed) in 1990, and Simitar would again release a letterboxed edition of MZ on video in DVD in 1998 (this time properly licensed) alongside the pan & scan “Godzilla vs. Monster Zero.” A new scan of “Monster Zero” was prepared for and shown on Monsters HD in the early 2000s and it’s this scan that the reconstruction on the 2007 Classic Media DVD is based on. The current version of “Monster Zero” on television (such as on Svengoolie) is the Classic Media reconstruction.