You may look at the list and think, "well that's most everyone isn't it" most people may only thing of a few of the more well known names, namely the few that were in the video games that didn't get in.
Toho has MANY monsters, most though connected with their own one shot movies or tv shows like Zone Fighters (I don't think IDW could get Mazinger or Zone Fighter if they wanted to LoL).
Well in semi-Alphabetical order, those not in the comics. and some info so you can look them up, or try to find the movies
Bagan (-was going to be in Mothra vs Bagan, script was re-worked to be "Godzilla and Mothra Battle for Earth")
Biollante( first movie: Godzilla vs Biollante)
-a giant plant, hybrid between Human/RoseBush/Godzilla
Baragon (first movie: Frankenstein conquers the world)
-dinosaur like monster that burrows through the ground
Ebirah (first movie: Godzilla vs the Sea Monster)
Godzilla Jr./Minilla/Minya (first movie: Son of Godzilla)
-okay yes I know "officially Godzilla jr and Minilla arn't the same monster according to Toho, but once I saw "Godzilla vs Space Godzilla" I said, "I don't care what they say, that's the same monster. The difference is less than that between 1970's Godzilla and Godzilla 2000.
Gorosaurus (first movie: King Kong escapes)
-rather generic looking dinosaur, size varies alot between apperance but can do a kangaroo kick
Jet Jaguar (first movie: Godzilla vs Megalon)
-Ultraman knock off, the result of a kid contest for a new monster
Kamacuras (first movie: Son of Godzilla)
-Giant Praying Mantis, american dub called them "Gi-Mantis". Honestly with Kumonga on the list I was surprised Kamacuras didn't make it
King Caesar (first movie: Godzilla vs Mecha-Godzilla)
-Golem god ShiShi
Manda (first movie: Atragon)
-like a chinese dragon mixed with a sea serpent, one of the few monsters that wasn't a guy in a rubber suit.
Mechani-Kong (first movie: King Kong Escapes)
-robot King Kong, yeah legal issues he aint' getting in any sooner than a giant King Kong would.
Megaguirus (first movie: Godzilla vs Megaguirus...with a note, the larval soldierd Meganulon were first seen in "Rodan", the winged Meganulon and Megaguirus came many decades later)
-giant dragonfly, also infamous for being a flying monster on a visible line in a movie past the year 2000
Megalon (first movie: Godzilla vs Megalon)
-Giant beetle with drill hands (can even switch between wrists somehow when holding hands together to form one big drill, lightning horn, and fire balls)
Moguera (first movie: The Mysterians, a remodled version would be seen in Godzilla vs Space Godzilla)
-a giant drilling robot
Oodaku (first movie: Godzilla vs King Kong)
-its a giant octopus
Orga (first movie: Godzilla 2000)
-alien that uses Godzilla cells to turn into a giant monster, personally I think the cloverfield monster is an anarexic knock off of this monster
Varan (first movie: Varan the Unbelievable)
-giant reptillian flying squirrel
Zilla *AKA Gino* (first movie: Godzilla "1998")
-giant dino-lizard, Toho offically re-named this monster "Zilla" and even had it in the movie (Godzilla Final Wars).
There is also a Zilla jr, from the American cartoon that came after the movie that has fire breath.
Toho has a few others, some like a random giant condor in "Godzilla vs the Sea monster" which I couldn't find an official name for, and many smaller monsters; none of the smaller ones seem to have nay ties to the Godzilla films. but there are two odd balls out that due to stock footage cameos and one monster seen dead in Final Wars do have some connection.
The Gargantuans (first movie: War of the Gargantuans)
-basically 300 foot tall bigfoots, a brown one which is nice to humans and lives on land, a green one which eats humans and lives in the water.
The Yog monsters (first movie: Space Amoeba, sometimes released as "Yog Monster from Space" trying to play it off like a Lovecraftian monster)
- these are three monsters
Gezora: a giant cuttlefish, which can even walk on land and has ice powers, considered by fans as the main monster of this movie.
Ganime: a giant crab, not much else, it gets blown up with dynamite, and a second one is created. Spits out seafoam
Kamoebas: a giant turtle. A dead one is in Tokyo SOS
There are also three models of Mecha-Godzilla, not much difference besides background.
Final wars also gives us: Monster-X which transforms into the giant quadraped three headed dragon "Keiser Ghidorah".
and the Rebirth of Mothra movies give us three other Ghidorahs.
-Des Ghidorah (a quadraped, smaller than Keiser Ghidorah), also known as "Death Ghidorah"
-Grand King Ghidorah (not that much different from King Ghidorah to be honest, only this ones like a cross between Galactus and King Ghidorah *feeds on life essence.
-Cretacious King Ghidorah (okay a picture speaks louder on this odd one)
http://images.wikia.com/godzilla/images ... idorah.jpg
The Rebirth of Mothra movies also have the pollution monster
http://images1.wikia.nocookie.net/__cb2 ... agahra.jpg
which also sheds off tiny star fish like parasites that are acidic.
the Rebirth of Mothra movies give us also Mothra-Leo *which is kind of odd in that through out the rebirth series it gains "power-ups" for lack of a better term. Aqua-Mothra, Armor Mothra, Rainbow Mothra, Eternal Mothra