The Foot Clan is a fictional Ninjutsu clan in the Teenage Mutant Ninja Turtles universe, and the Turtles' main antagonists. It is usually led by The Shredder.

The Foot Clan was originally inspired by the criminal ninja clan The Hand in the Daredevil comics. In addition to the obvious similarity in their names, both clans originate from Feudal Japan, practice Ninjutsu and black magic, and are now powerful global organized crime rings.

Source: Wikipedia