Randall Marijuana's Cat/C-Artemis
From Blaseball Wiki
It's Artemis's job to hunt the mice in the house. This is tough job, due to the newly introduced species of Demon Mice that crawl up from the Hellmouth. Though difficult, Artemis is adept at capturing these mice and returning them to the arena, where they become the imps' problem. The only compensation she demands is scratches behind the ears.