Chaos Galaxia was the result of Chaos taking total control of Sailor Galaxia's subconscious mind and body.
Her appearance is almost the same as that of Sailor Galaxia, except that the golden parts of her sailor fuku are now black. Her hair is a blood red color, her skin is grey in color and she has golden eyes. She also had two black bat-like wings; with which she used to fly.
Chaos Galaxia's first and only appearance was in the series finale of the original anime's fifth season. Chaos, after realizing that Eternal Sailor Moon, who has transformed into Princess Serenity, was trying to seal both it and Galaxia at the same time, it shattered her bracelets and completely took control of her. She challenges Serenity to a sword fight, who refuses to do so. She explains to Serenity that her goal is to end the Sailor Wars and destroy the Light of Hope. She battles Serenity until she is accidentally wounded by her, when the Sword of Sealing pierces through her right wing. Galaxia, in anger, destroys the sword, resulting in Eternal Sailor Chibi-Chibi's death, who had shape-shifted into the mystical Sword of Sealing to assist Princess Serenity.
Serenity transforms herself into a nude, angelic form and exposes the immeasurable healing power of the Silver Crystal, her very own star seed. Chaos Galaxia becomes tensed and tries to throw off and kill Sailor Moon. During a final attempt to keep her away, Galaxia's sword shatters, and her former self slowly awakens. Sailor Moon holds her hand, supporting Galaxia until she utterly expelled Chaos from her body.
Chaos Galaxia was totally evil, as Chaos was the one in control. She was easily angered, and desired to destroy the entire Galaxy.
Chaos Galaxia was a stronger form of Sailor Galaxia. When Chaos took control, her power was boosted with his own. Making her even stronger than the Light of Hope itself.
- Dark Energy Beam - Chaos Galaxia sends a beam of dark energy by swinging her sword toward an enemy.
- Dark Energy Barrage - Possibly her stronger attack, Chaos Galaxia could fire a massive barrage of her dark energy around her enemy, causing them damage from its power.
Sword: Chaos Galaxia still held Sailor Galaxia's sword of evil power. And was able to use it efficiently.
- This form of Galaxia is always confused by fans to be Sailor Chaos. In the manga, Sailor Chaos does have a slight resemblance to Galaxia. However, Sailor Chaos is the Sailor Soldier form of Chaos and not Sailor Galaxia completely taken over by Chaos.
- This form was never given a name in the anime. However, on an official trading card printed by Amada, she was named Chaos Galaxia.
- The musical-only character Sailor Buttress shares a strong resemblance to Chaos Galaxia.