The Monkeys of Montevideo were a group of thirteen monkeys with mysterious powers.
It was believed that sacrificing all thirteen of them would give whoever did so power to control the seas.
LeChuck sought out the monkeys and was almost ready to complete the ritual when he was stopped by Guybrush Threepwood.
On being returned to human form, he and Elaine Marley began the process of returning the monkeys to their rightful homes.