| Spoiler warning!|
This article contains spoilers from the game.
Princess Celestia is an ally character in Ponyvania: Order of Equestria.
At the beginning, Celestia, being the head of the Order of Equestria, resides in the room to the far right of the palace. She informs the player that Discord is going to break out of his seal, and tasks the player with stopping him. In order to do that, she gives the player the mission to track down the lost Elements of Harmony to seal him again.
Most of the time, Princess Celestia provides the player with information about where to go next.
At some point, possibly when she goes out of the order's HQ and leaves Twisted Horn, Celestia gets ensnared and stolen her identity by Queen Chrysalis. After the player's long travel, Celestia is freed from a cocoon in the throne room of Canterlot Castle. She and Luna determine the position of Discord's hideout, Realm of Chaos, then they open a portal for the player.
After the player deplete Discord's strength, Celestia and Luna teleport to them and use Elements of Harmony to reseal Discord, then the sisters teleports everyone back to the throne room.
When the player is on the way to leave Equestria, Celestia and Luna comes to see the player's off at somewhere outside Canterlot. They are greatful to the player's effort, and allows him/her to come back to Equestria at any time.
In the alternative story of bad ending, right after Celestia is freed in the throne room, she says the chaos Discord brought to the land must be cleansed first. Then, the game shows the scene of failed quests and Game Over screen.