Hyrule Warriors: Age of Calamity has a bunch of secrets for players to explore and tons of playable characters to try out and fight as on the battlefield.
While most characters are unlocked by just playing through the main quest, there are a handful of secret characters that can also be unlocked through alternative means. These include the following:
The Great Fairy’s will unlock sometime after Chapter 2. A sub quest will open on the map with their faces on. Completing the quest will unlock another one three times more. Completing all these mini quests will unlock the Great Fairy as a playable character.
Monk Maz Koshia
After proceeding through the Main Quest, you will unlock three Monk subquests in the map eventually. Giving the resources needed to these three quests will unlock a fight with the Monk. Defeat him and you will gain him as a character.
Terrako The Mini Guardian
The Mini Guardian can be unlocked after completing the Main Quest. You must complete all of its sub quests scattered across the world to gain the parts needed to repair it.
Ganon’s sub quest mission will unlock eventually through the game in the southeast. It will be titled “Vs. Calamity Ganon” and by completing it, you’ll unlock the final secret character.