The Grand Finale Galaxy is the final galaxy in Super Mario Galaxy. The galaxy is where Mario's home planet, the Mushroom World, resides. The galaxy is unlocked once both Mario and Luigi collect 120 Power Stars, and can be reached by talking to the fourth Green Luma on the Trial Planet. This galaxy has the 121st Power Star for both Mario and Luigi. The level takes place in Toad Town from the beginning of the game, except that Penguins, Bees, Gearmos, and Star Bunnies are here. The Toad Brigade and their Starshroom, are found outside of Peach's Castle. After collecting all 100 Purple Coins, Mailtoad will receive a letter. If the player talks to him, they will receive a congratulatory letter on the Wii's Message Board. The picture of the congratulatory letter differs depending if the player spoke to Mailtoad as Mario or Luigi. The picture can be sent to friends. On the list of galaxies, the Grand Finale Galaxy is called "Grand Finale" lacking the "Galaxy" name that all other galaxies use.
This is the main and only planet of the galaxy, and is where other Mario games take place. This game (Super Mario Galaxy) only shows Peach's Castle and Toad Town however. The castle and area is based off its look from Super Mario 64. The area contains an enormous lake with a river flowing into it and a pathway to Toad Town. The path goes through the town, and into the Castle. There is an invisible wall blocking the entrance to Peach's Castle just like in Super Mario 64.
The Star Festival
The Star Festival is the only level of the Grand Finale Galaxy. It requires the player all 100 Purple Coins. After collecting all 100 Purple Coins, Mario/Luigi will receive the 121st Power Star. However, before collecting the Star, Mario/Luigi must talk to Mailtoad to receive a congratulatory message and attached picture on the Wii's Message Board. This mission is named after the event at the beginning of the game, which occurs every 100 years.
- Although Peach's Castle can be seen, an invisble wall blocks the entrance of the Castle, probably because the Peach's Castle area has not been designed and closed off from the player (like an unfinished building being constructed).
- Altough this galaxy does not contain any Black Holes, it is still possible to die from fire damage on the campfire after talking to Captain Toad.