Toho

Founded in 1932, Toho Co. is basically responsible for the entirety of the tokusatsu genre. It specializes in Kaiju movies, and brought us the King of the Monsters himself.

They actually have a lot more to their catalog of films, including many much more down to earth stories, but that's what most people remember them for.

That and Akira Kurosawa.

They also acted as distributor or co-producer for Studio Ghibli and many other anime films you may have heard of, as well as many of the live action film adaptations of anime that crop up from time to time (Nana, Space Battleship Yamato, etc). They also provided production facilities and some actors for the James Bond film You Only Live Twice.

Not to be confused with Touhou.

Toho is responsible, associated with or known for:

 * Akira Kurosawa
 * Gamera - Distributed the Heisei films.
 * Godzilla
 * Kaiju
 * Rodan (1956)
 * The Mysterians (1957)
 * Varan the Unbelievable (1958)
 * The Three Treasures (1959)
 * Mothra (1961)
 * Gorath (1962)
 * Atragon (1963)
 * Dogora (1964)
 * Frankenstein Conquers the World (1965)
 * War of the Gargantuas (1966)
 * King Kong Escapes (1967)
 * Latitude Zero (1969)
 * Space Amoeba (1970)
 * Yamato Takeru (1994)
 * Rebirth of Mothra (1996)
 * Rebirth of Mothra 2 (1997)
 * Rebirth of Mothra 3 (1998)
 * Ringu
 * Toku
 * Battle in Outer Space (1959)
 * The War In Space (1977)