- Not to be confused with Bowser's Galaxy Reactor.
- “I can feel a Grand Star nearby! But this place is filled with all kinds of traps and tricks! Be careful!”
- —Luma, Super Mario Galaxy
Bowser's Star Reactor is a galaxy located in Super Mario Galaxy and the first galaxy where Mario fights Bowser. Before that, he has to travel through a short level. The galaxy has lots of inaccessible Airships floating in the background; these can only be reached by hacking the game, which reveals they are solid. The theme is a remix of Bowser's Road from Super Mario 64.
Planets/Areas
NOTE: Unless otherwise noted, all names are unofficial.
Starting Planet
This Planet contains Firebars and a 1-Up Mushroom. When the player advances on the platforms, they will go into a loop. This planet also has a Thwomp and a flamethrower, and a platform that takes Mario to the Gravity Planet.
Gravity Area
Here, Mario must be careful as to not fall off the platforms and into a Black Hole, because the gravity changes back and forth here due to the Gravity Walls. There are also more Firebars and a Thwomp here. At the end of this area is a platform leading to the stairs.
Stairway
In this area, there are stairs that lead to the platform where Mario fights Bowser. There are yet more Firebars, flamethrowers, and Thwomps that make getting to the top harder. After the Firebars, Bowser will appear and then he will try to throw fireballs at Mario. When the player reaches Bowser, they will be taken to the Magma Planet.
Star Reactor
This is the planet where Mario battles Bowser. When Bowser Ground Pounds the blue glass, lava will be exposed and burn his tail. The green plates can be used to block the shock waves Bowser makes. When Bowser is defeated, Mario will receive a Grand Star, unlocking the Kitchen.
Missions
This galaxy consists of only the following mission.
| Level | Image | Summary |
|---|---|---|
| The Fiery Stronghold | 
|
This mission's objective is to defeat Bowser. |
Gallery
The main platform of the level.
One of the stars for decoration when Mario reaches Bowser.
Mario and Bowser about to faceoff.
