|Romanization||Myūtanto Nezumi (Mutant Mouse)|
|Average height||2 meters (Small)|
|Average length||4 meters (Small)|
|Average weight||600 pounds (Small)|
|Place of origin||Earth|
|Habitat||New York City, New York|
|Status||Extinct (Small & Medium Giants)|
Critically Endangered (Large Giants)
|Behind the Scenes|
|Universe||Godzilla: The Series|
|Performed by||Pig vocals|
The Giant Rats are a trio of mutations incurred in at least one species of rat within New York City, New York, United States of America. They have all evolved from the city's brown rats; it is not clear why no black rats were witnessed having mutated, as well.
These rats possess some dangerous traits, though their abilities are segregated by their overall size. Small Giant Rats for instance are agile creatures, showing amazing speed and extraordinary jumping capability, being able to outrun Zilla Junior and jump on top of short buildings, respectively. Medium Giant Rats are instead known to be able to carry a human in one arm, with no sign of struggle. The Large Giant Rats are by far the most durable, being much stronger than the other two types known.
In 1998, a single Giant Rat was seen in New York City, prompting H.E.A.T to move Zilla Junior to the area in order to capture it. Complicating matters, three redneck hunters had also arrived in order to hunt the creature, only to discover dozens more of the mutations in the bowels of the city. This led to the military being called in, though H.E.A.T and the hunters were unable to escape the tunnels before the bombing run. Zilla proceeded to flood the rats' various tunnels while a team enters the area and successfully rescues H.E.A.T. However, one of the largest of the rat mutants survived the flooding and was then discovered by the Tachyons, an invading alien race who moved the creature to their base of operations, Site Omega on Moansta Island. Though present during the launch of the invasion, for some reason it didn't take part and instead mysteriously disappeared after the ensuing events. It can be presumed given similar events during the invasion that it had simply regained control of its mind somehow and wandered off, continuing its existence elsewhere.
- Godzilla: The Series: Cat and Mouse (1998) (First appearance)