Queen Metalia is an evil force sealed under Planet Earth. She fed on human energy and was mysteriously connected to the Silver Crystal. Queen Beryl used her to wage war against the Moon Kingdom in the past and tried to awaken and control her in the present so that her Dark Kingdom could take over the world.
Queen Metalia appeared as purple energy contained within a crystal pillar. Her color would flash red when she recovered her strength, and the inside of her pillar was also shown to be a stream of red energy. The pillar containing Queen Metalia was located in the Dark Kingdom, which appeared to be an underground fortress built around her.
Queen Metalia was an incorporeal force that fed on human energy. She was mysteriously linked to the Silver Crystal and gained strength whenever it was used. According to Queen Beryl, Metalia and the Crystal's power was the same, meaning Metalia was Earth's counterpart to the Moon's Silver Crystal. Metalia possessed a very limited consciousness, and was only able to speak the words "planet" and "destroy". Her only purpose was to destroy planet Earth, under which she was sealed.
At the end of the Silver Millennium, Queen Metalia was the entity that granted Beryl the power to start a revolution on Earth against the Moon Kingdom and Endymion. During the revolution, Endymion was killed, and the grief caused Princess Serenity to unleash the power of the Silver Crystal, therefore destroying both the Moon and the Earth. During this event, Metalia was somehow sealed underground.
After being reborn in the present, Queen Beryl attempted to awaken and control Queen Metalia in order to rule over the Earth. Using Metalia's power, Beryl revived the Shitennou and brainwashed them to make them forget their previous lives, with varying degrees of success. At first, Queen Beryl tried to awaken Metalia by feeding her energy from humans on Earth, collected by the Shitennou's Youma, and by finding the Silver Crystal.
Even though the Dark Kingdom failed to find the Crystal, Beryl managed to partially awaken Metalia using human energy. After Usagi awakened as Princess Serenity and the Silver Crystal revealed itself, Metalia's powers began to grow rapidly, much to Queen Beryl's puzzlement.
Sometime after the Princess and the Silver Crystal revealed themselves, Queen Beryl figured out that Queen Metalia's power was connected to the power of the Silver Crystal; whenever Usagi used the Silver Crystal's power, Metalia's own strength would increase.
As Metalia began to awaken on her own, she started summoning identical cloaked Youma without Queen Beryl or the Shitennou's intervention. These Youma were weak, but they always appeared in groups. Eventually, Metalia's strength increased to the point where her Youma were able to combine into single, more powerful Youma capable of draining energy from the people of Tokyo, leaving them comatose. Metalia herself later possessed one of these strong Youma, but was forced out of its body by Sailor Venus' Rolling Heart Vibration, allowing Sailor Moon to destroy it.
Metalia's growing power was a cause of concern for Queen Beryl, who feared that the entity would destroy the Earth before she had the chance to take over it. Beryl attempted to drain Metalia's power through different ways, but she was unsuccessful. In the end, Mamoru decided to seal Queen Metalia within his body, believing that he could contain it, much like Usagi contained the Silver Crystal within hers.
However, Metalia's power manages to corrupt Mamoru after he witnesses Kunzite's death, and turns him into the entity known as Metalia Endymion, a dark version of Prince Endymion whose only mission was to destroy the planet. Metalia Endymion defeats the Sailor Guardians in combat until Sailor Moon stabs the entity with Endymion's sword, effectively killing both Mamoru and Queen Metalia and putting an end to the Dark Kingdom.
Metalia's dead, empty pillar remained in the Dark Kingdom's base, and Queen Beryl chose to die in its chamber as her castle collapsed.
- In the manga and anime, Queen Metalia was stated to be a demon from the sun. In Pretty Guardian Sailor Moon, Metalia's origin was left unexplained, but she was linked to the Earth and the Silver Crystal.
- Unlike her counterparts in other versions of the Dark Kingdom arc, Pretty Guardian Sailor Moon's Metalia could not speak on her own beyond her desire to destroy the planet.
- Also unlike other versions of the Dark Kingdom arc, Metalia was not the final enemy of the Pretty Guardian Sailor Moon series. The Sailor Guardians had to fight both Princess Sailor Moon and Queen Mio after Metalia's demise.
- Metalia's voice actor is Miyuu Sawai, who played Usagi and Princess Sailor Moon. Her voice was digitally altered for Metalia's role.