Rhett the rat

 '"Frankly my dear, Rhett the Rat doesn't give a damage about the destruction he unleashes. The villainous vermin scurries from city to city running, jumping and destroying all that stand in his way. You won't find this dirty rat hanging out in the dark alleys - and if you do, you better hope you're the one that can scurry away!"

- Rampage: Total Destruction

Background
Rhett drank some Scum Soda and had a violent reaction, which turned him into a rat-like monster.