Phantom Aqua is an antagonist in Kingdom Hearts 0.2 Birth by Sleep -A fragmentary passage-. She is a phantom version of Aqua, the personification of her doubts and insecurities, and is encountered in the Realm of Darkness.
When Aqua finds herself in the remnants of Dwarf Woodlands, she finds a mysterious mirror. Her reflection comes to life and pulls her inside. Trapped, Aqua solves the mysteries of several other mirrors, all while being taunted by Phantom Aqua, and engages the copy in battle three times. Once Phantom Aqua is destroyed, the real Aqua is able to proceed on her journey.
As a copy of Aqua, Phantom Aqua has all of the real Aqua's abilities, even wielding a copy of the Master's Defender Keyblade. In battle, Phantom Aqua teleports, creates doppelgängers, and spawns large ice crystals to attack her enemies. Phantom Aqua can also use the Spellweaver Command Style.