Sewer Rats are rodent monsters found in the Dungeons of Fate.
Sewer rats are darker, larger, stronger versions of the Rat. For every Sewer Rat there are several Normal Rats. There is a spell called Summon Rat, which summons 3 low level Sewer Rats. If you use a cheat and summon a Sewer Rat it spawns with several more regular Rats.