Bedroom (Super Mario Galaxy)
From the Super Mario Wiki
The Bedroom is a dome in Super Mario Galaxy. It is the fourth accessible dome, and can be unlocked once Mario or Luigi recovers the Grand Star from Bowser Jr.'s Airship Armada. It is presumably Rosalina's bedroom, and its main boss is Bowser.
The Bedroom has purple walls and a curtain that hangs outside. Inside the dome is a purple starry wallpaper, some curtains, and a large canopy bed. It is the first dome to have three major galaxies, rather than two. As all domes, the bedroom has a Pull Star in the middle which is used to access the dome's Galaxies.
This dome and the Engine Room are the only domes with three main galaxies and an enemy base. However, since this dome's Dusty Dune Galaxy has an extra Green Power Star, the Bedroom outnumbers the Engine Room by 1 star, making it the dome with the most stars in the game.