Giant rat

Giant rats are simply an oversized version of these common rodents. This set of rodents just love to sink their teeth into your flesh. They vary greatly in strength, from ones the size of a cat to ones bigger than humans, like their mole rat cousins. They can be annoying - the rats are hostile and will begin combat if you draw too near, severely delaying the player's passage through rat-infested areas.And the Rats outside 13 have become a sort of meme to fallout fans

Small
The smaller rats are still big enough to rival a dog in size. They usually attack in large groups and could visually appear out of nowhere. They differentiate in color, being black, grey and even white. They appear in the Core Region, as well as in Texas.

Big
These rats are even bigger than the mole rats and humans. Their visible spine gives them disturbing appereance, while their size and power could prove a challenge for an unexperienced wastelander. They can be found in the Midwest and Texas.