The Colossal Titan (Attack on Titan)
The "second" Colossal Titan (Attack on Titan)
Slifer the Sky Dragon (Yu-Gi-Oh!)
The Winged Dragon of Ra (Yu-Gi-Oh!)
The Titans (Skylanders) are a race of giant monsters that are so massive that they use volcanoes for hot tubs!
Levia-chan (Princess Lucia) is a leviathan child.
Behe (Princess Lucia) is a behemoth child.
Ziz (Princess Lucia) is a ziz child.
The Ten Tails (Naruto), the Creator and Destroyer of the World.
Gyūki, the Eight Tails (Naruto)
Kurama, the Nine-Tailed Demon Fox (Naruto)
Godzilla (Godzilla) firing his Atomic Breath.
Zilla (Godzilla) is a monstrosity of unimaginable proportion.
The monster from (Cloverfield)
a Lesser Titan (Age of Mythology: The Titans)
The Great Devourer (Lego Ninjago: Masters of Spinjitzu)
After gathering enough negative energy, Fanoxean (The Young Guardians) can transform into a colossal beast with immense power.
Ayon (Bleach) is an enormous chimeric Hollow.
Due to being the result of countless Hollows merging together, Gillians (Bleach) are Hollows the larger than buildings.
Choe Neng Poww (Bleach) in his released form, Calderon.
Yammy Llargo (Bleach) in his released form, Ira.
Yammy Llargo (Bleach) in his Enraged Form.
(Pacific Rim) Comparing size of humans and Kaijus
Po Kong (Jackie Chan Adventures) also called a Kaiju to Japanese.
Devastation caused by a Kaiju.
Jet Jaguar (Godzilla) is a Mecha Kaiju.
Spacegodzilla (Godzilla) a Mutant Kaiju.
King Caesar (Godzilla) is an Earth Based Kaiju.
Monster X (Godzilla) is an Alien Kaiju.
Kiryu (Godzilla) is a Mecha Kaiju.
Tursacra (Kaiju Combat) is a powerful earth-type giant monster.
Scaos The Sinkeeper (Kaiju Combat)
Heart Eater (Kaiju Combat)
Dragon Lotus (Kaiju Combat)
Macrosaurus (Kaiju Combat)
Shadowheart (Kaiju Combat)
Mecha Stego Maximo (Kaiju Combat)
Cavorsteain (Kaiju Combat)
Shadow of Red (Kaiju Combat)
Tri'Moloch (Kaiju Combat)
Hound of Nita (Kaiju Combat)
Nightstone Manor (Kaiju Combat)
A Category V Kaiju (Pacific Rim)
Fenrir (Valkyrie Crusade)
Yamata No Orochi (Yaiba) is the most massive monster in the entire series as well as the entire country of japan itself.
Chimera’s (Marchen Awakens Romance) denial of her humanity allowed her to obtain the monstrous power of the Ghost ÄRM, Hydra. With her memories erased, Chimera shares the body and the mind of the vile creature the ÄRM fused her with.
Oozaru/Great Apes (Dragon Ball Z)
After it broke, the Darkness ÄRM, Finsternis' compensation mutated Saturn (Marchen Awakens Romance) into a giant canine monster.
After his Shin Kuria Seunousu spell was destroyed, Clear Note (Zatch Bell!) was able to undergo his final transformation into a colossal monster. In this form, Clear has enough power to annihilate all that exists.
Nega-Suu (Monster Musume) is a colossal and highly dangerous & destructive Slime.
Before Ragnarok, Fenrir (Norse Mythology) will be freed and will go forth with his mouth opened wide, his upper jaw touching the sky and his lower jaw the earth.
Jörmungandr, the World Serpent (Norse Mythology) is so large that it was able to surround the earth and grasp its own tail.
After assimilating with their Household Spirits, Seiryu and Kokuhyou (Magi The Labyrinth of Magic) transform into monstrous versions of Hakuryuu Djinns Zagan and Belial.
SCP-3700 (SCP Foundation) is an area in the North Sea where the Orcadian spirits Sea Mither and Teran fight in an endless cycle of death and rebirth in the forms of a six kilometer tall European Lobster (SCP-3700-1) and a 32 kilometer long pelican eel (SCP-3700-2).
Todd Ziller/American Kaiju (Marvel Comics) was transformed into a giant monster after being exposed to Gamma enhancements, Mutant Growth Hormone, Pym Particles and the Lizard Formula by Project Troubleshooter, the US Military's latest program meant to recreate the Super-Soldier Serum.
A Horrorterror (Homestuck)
Gamera, the Giant Monster Turtle (Gamera Series) a friend of humanity and eternel rival of Godzilla.
Obelisk the Tormentor (Yu-Gi-Oh!), the second strongest of Egyptian God Monsters.
VenomMyotismon (Digimon) is a Demon Beast Digimon as big as skyscrapers.
Arcadiamon Ultra (Digimon)
Belloc Rosenblatt (Firebreather) is the King of the Dragons/Kaiju.
Durin's Bane (Lord of the Rings), a Balrog of Morgoth.