Shadow

In Paper Mario: The Thousand-Year Door, Beldam, Marilyn, and Vivian (who was later replaced with Doopliss, since she ended up joining Mario's party) worked with the X-Nauts and their leader, Sir Grodus to find the seven Crystal Stars and use them to break the seal on the Thousand-Year Door and release the Shadow Queen. Grodus' intention was to use her power to destroy the world, remake it in his own image, and become its ruler. However, the Shadow Sirens, as well as the Shadow Queen herself, had other plans.