Rats (Rattus) are a species of rodents native to Earth.
Ratcatcher was a criminal who used rats to carry out crimes in. However, after he died from drug overdose, his daughter and protege, Cleo Cazo became a criminal known as Ratcatcher 2, and trained rats to carry out crimes in her father's honor. At some point, she adopted a rat that she named Sebastian.
Corto Maltese Mission
During the Corto Maltese mission, Ratcatcher 2 was made to join to Task Force X, where she used her rat mind control to help the team on various occasions. The rats of Corto Maltese were ultimately responsible for ending Starro's rampage under her control.