What collectibles are needed to unlock the Thousand-Year Door?

The collectibles needed to unlock the Thousand-Year Door are the seven Crystal Stars.

Mario learns that the Crystal Stars reveal the locations of the legendary treasure and provide the power required to open the ancient door beneath Rogueport. Each star is tied to a different chapter and is generally obtained after Mario overcomes a major regional challenge or boss.

The stars also serve a gameplay purpose. Every Crystal Star Mario collects unlocks a new special move and increases his Star Power, giving the collectibles both narrative importance and a direct effect in battle. Their locations are revealed through the magical treasure map connected to the Thousand-Year Door.

Players sometimes confuse Crystal Stars with the game’s other important objects, such as badges, Shine Sprites, or Star Points. Those items help with abilities, upgrades, or character progression, but they do not open the door. The seven Crystal Stars are the story-critical collectibles, and the X-Nauts and Bowser also pursue them for their own plans.