Castle Nox is a location in Fire Emblem: Radiant Dawn, located north of Tor Garen in southern Daein. It is the setting for Chapter 13 of Part 3. This chapter is a Defend chapter, which requires the player to prevent the enemy from crossing the designated green line for 12 turns. It is a fortified castle where the Daein army retreats to after failing to assassinate the Apostle Sanaki in an ambush in the previous chapter. Here, King Pelleas attempts to absolve the Blood Pact by his own death, and may or may not be spared depending on the player's choice and depending on whether it is the first playthrough of the game or not.
Castle Nox is covered in snow and is defended by a heavy artillery regiment of Ballistae and Stone Throwers. Part of the castle rampart was destroyed in a cutscene when Goldoa's Prince Kurthnaga arrives in dragon form in an attempt to halt the battle.