Big Star Door
From the Super Mario Wiki
Ads keep the MarioWiki independent and free :)
Big Star Doors are doors that restrict progress to certain required parts of the game until the player has the necessary number of Power Stars. They have appeared in Super Mario 64 and its remake Super Mario 64 DS inside Princess Peach's Castle. Like most locked doors in these games, a certain number of Power Stars must be obtained before they can be opened (although Big Star Doors require many more Power Stars than regular doors). Once unlocked, the doors will slide open allowing Mario to enter. Only Mario can unlock a Big Star Door, but once it is unlocked, any character can enter it.
Four Big Star Doors exist in the games:
In the Super Mario Mash-Up Pack in Minecraft, there is a painting of a Big Star Door.