Rats are one of the most common monsters in roguelike games.
In reality, a rat can be a good pet, but such is not common in roguelikes. They are, however, suitable for the role of a familiar, should a game implement such a role. Rats may be encountered singly or in groups. In games where monsters can rapidly multiply, this power can represent the formation of large hordes of rats.
Rats have an exceptionally keen sense of taste. How to reflect this in a roguelike is a challenge for the developer looking for an exciting new take on rats.
Many variants on the rat are possible. Giant rats are obvious and common. They can also carry disease or even be rabid. Crawl has rats in strange colors. Elemental rats, undead rats, mutant rats, and many other rat variants can be explored. Never discount the utility of the rat.