The Secret Society of X-Nauts is an alien organization which tried to take over the Mushroom World. They are the main enemies in Paper Mario: The Thousand Year Door.
The organization built their base on the moon and connected it with the town of Rogueport via a teleporter. This base was run by a giant computer, which later betrayed the organization. They also used their technological prowess to a manufacture weapons, ranging from gigantic battleships to robotic armor, as well as creating many creatures to serve as soldiers. Their goal in the game is to find all the Crystal Stars in order to unlock the Thousand Year Door and use the Shadow Queen to take over the Mushroom World. At the end of the game the only a couple of X-Naut soldiers, Grodus' head and, Crump remain. The Secret Society of X-Nauts have goals and a military set up similar to the National Socialist German Worker's Party.
Sir Grodus is the strict leader of the X-Nauts has his sights set on world domination.
The Shadow Sirens
Shadow Sirens are a group of three witches that work for X-Nauts and told Grodus of the Thousand Year Door (?). Vivian joined Mario and she was replaced with Doopliss.
X Naut Soldier
A common X-Naut soldier that is the common footsoldier.
The scientists who experiment in creating soldiers like the Yux. They attack using various potions.
The strongest of the soldiers.
X shaped creatures that shoot laser rings at their enemy and can create shields. They were created by X-Naut PHDs in labs for security. They're are many different types.
- Magnus von Grapple- A gigantic robot with rockets used by Lord Crump.
- Magnus von Grapple 2.0- A new model of Magnus von Grapple that has more weaponry and was powered by the Crystal Star.
- Battleship- An X-Naut ship used for battle. It has a large cannon and the ship is entirely made out of metal.