After residing in a swamp for several months, the Rat King (who remains unnamed until the end of the issue) decides to venture into a nearby abandoned industrial park and use it as shelter against the oncoming winter.

[2] Despite being a minor character in the Mirage comics at the time of its initial airing, the Rat King (voiced by Townsend Coleman) is featured as a recurring character in the 1987 Teenage Mutant Ninja Turtles animated series, being one of the few villains from the Mirage comics to make the transition into the cartoon (the others being the Shredder, The Foot Clan, the Triceratons, and Dr. Stockman).

[3] The cartoon version of the Rat King was also depicted as highly intelligent, shown to be able to create such things as various chemical concoctions and bombs.

[7] Though mentioned throughout "The Future Shark Trilogy", the Rat King only appears in person in the story-arc's last issue, which has him engaging in a battle royal with the Turtles, their allies and several other villains.

In this series' season 1, the Rat King was introduced as Victor Falco, a scientist working on a neurochemical that allows him to read thoughts, and ultimately, to anticipate every move the Turtles make.

In the IDW comic book series, the Rat King is a member of the Pantheon, a group of demigods who once influenced humanity's evolution as a sort of competition among themselves.

Scheming to become the ultimate winner in this "game", the Rat King begins pitting the Turtles and their enemies against each other until his brother Chi-You brings the conflict to an explosive conclusion which temporarily takes out the whole Pantheon.

[10] The Rat King also appears as a boss and unlockable playable character in the Super NES version of Teenage Mutant Ninja Turtles: Tournament Fighters.