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 reaches the remnants of Dwarf Woodlands, she finds a mysterious mirror. Her reflection, "Phantom Aqua", comes to life and pulls her inside its mirror realm, where her true reflection is stolen by three identical magic mirrors. As Aqua explores this realm in order to escape, Phantom Aqua taunts her by claiming that her actions are futile and that nobody cares about her. Each time Aqua locates one of the three mirrors, Phantom Aqua attacks her, but is defeated. Once Phantom Aqua is destroyed after the third battle, Aqua is able to escape the realm and continue her journey, but the phantom's taunts continue to pain her.
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.