Rats are animals that live on both Mobius and the many interpretations of Planet Earth in Sonic the Comic. Many appear as non-anthropomorphic rodents, although there are a few minor characters:
Rat Bratt is a nasty rat from out of town who appears to be unhappy with Tails' defence of Mobius. He challenges Tails to a race, which he appears to somehow win, despite Tails being much faster when flying. The fox discovers that Bratt had a twin brother who kept racing ahead to the next checkpoint by helicopter but was discovered when his brother wanted some of the credit.
Rats often appear in Castle Frank N. Stein. One particular rat campaigned for equal rights for rodents and another let us know that they have feelings. In the dungeon, a vampire rat exists and let his friends know that Chuck D. Head was coming down for "dinner".