Inspired by Jules' Godzilla vs. The Smog Monster/Frog double feature I decided to compile a list of all the original U.S. double-bills for Japanese sci-fi films. 

All Japanese films have been listed using their original U.S. release titles.

This list can be expanded by all members....

• Godzilla, King of the Monsters! / Quincannon, Frontier Scout (June 1956) (Loew's Brooklyn theaters)

• Godzilla, King of the Monsters!/A Strange Adventure (July 1956) (original saturation release at Southern Californian Fox West Coast theaters and Pacific drive ins) 

• Godzilla, King of the Monsters! / Swamp Women (August 1956) (most Chicago theaters via Capitol Films)

• Half-Human: The Story of the Abominable Snow Man/Monster from a Green Hell  (May 1957) (official distributor package)
  
  
• Rodan / Hell in Korea (November 1957) (official distributor package)
  
  
• The Mysterians / First Man Into Space (May 1959) (official distributor package)

• Gigantis the Fire Monster / Teenagers from Outer Space (May 21, 1959) (official distributor package)

• The H-Man/The Woman Eater (June 23, 1959) (official distributor package)

• Gigantis the Fire Monster / Rodan (June 24, 1959) (NY metro area saturation release)

• Battle in Outer Space / 12 to the Moon (July 8 1960) (official distributor package)

• I Bombed Pearl Harbor / Then There Were Three (November 1961) (official distributor package)

• Mothra / The Three Stooges in Orbit (July 1962) (saturation release in NY metro area on the RKO circuit and other theaters) (no official distributor package)

• The Manster/The Horror Chamber of Dr. Faustus (March 28, 1962) (official distributor package)

• Varan the Unbelievable / First Spaceship on Venus (December 7, 1962) (official distributor package)

• King Kong vs. Godzilla/The Traitors (June 1963) (RKO circuit in NY)

• King Kong vs. Godzilla / Terrified (July 1963) (Southern Cali saturation release at all drive-ins and most theaters)

• Gorath / The Human Vapor (preview showing in November 1963 in Arizona, showings in Southern Cali, Arizona and Honolulu starting May 1964, expansion to rest of mainland in 1968) (official package)

• Godzilla vs. The Thing/Voyage to the End of the Universe (September 17, 1964) (official distributor package)

• Atragon / The Time Travelers (December 1964) (official distributor package)

• The Lost World of Sinbad/War of the Zombies (March 1965) (official distributor package)

• Ghidrah, the Three-Headed Monster / Harum Scarum (December, 1965) (NY metro area saturation release) (no official package)
  

• Frankenstein Conquers the World/Tarzan and the Valley of Gold (July 8, 1966) (official distributor package)

• Gammera the Invincible / Knives of the Avenger (official package beginning in July 1967)

• Monster Zero/War of the Gargantuas (July 29, 1970) (official distributor package)

• Godzilla’s Revenge/Island of the Burning Damned (December 8, 1971) (official distributor package)

• Godzilla vs. the Smog Monster/Frogs (July 1972) (NY metro area at most theaters) (no official package)