Negaforce

The Negaforce is an evil being in the anime Sailor Moon. Queen Beryl, the ruler of the Negaverse, is out to gather energy to release her. In the Japanese version of the manga, she is called Queen Metallia. The The re-released Sailor Moon manga romanizes her name as "Metaria".

Anime
In the second to last episode of the first season, she is shown in a giant, slightly humanoid shadow form as she defeated Sailor Mercury, Sailor Mars, Sailor Jupiter, and Sailor Venus after easily withstanding their attacks, and was sealed inside the Imperium Silver Crystal along with Beryl and her minions by Queen Serenity. They eventually got out, but the Negaforce was unable to use much of her power, residing inside a red orb from which Beryl and her minions intended to release her by gathering energy and finding the Imperium Silver Crystal.

Though she is mentioned in the very first episode, her first actual appearance was in "Episode 21", being given energy by Queen Beryl, and telling her to find the Rainbow Crystals.

In "Episode 40", after Beryl was defeated by Tuxedo Mask, she asked the Negaforce how to win. The Negaforce told her that she was nearly as incompetent as her minions, but decided to give her one last chance, and broke out of the red orb she was encased in and combined with Queen Beryl to form a gigantic Beryl with blue skin and hair. There, she fought Sailor Moon. During the battle, Sailor Moon turned into the Moon Princess, Princess Serena, and, powered up by the spirits of the other four Sailor Scouts, used Cosmic Moon Power to destroy Beryl, the Negaforce, and the Negaverse with an energy ball.

Manga
In the manga, Metallia is an entity that was created by abnormal activity in the sun. Soon afterwards, there was a meteor shower, during which Metallia fell to Earth. She resided on Earth for a while until she met a servant girl named Beryl. Metallia manipulated Beryl, appealing to her feelings of greed, hatred, and jealousy. She then continued to manipulate other people of the Earth by appealing to their greed and desire for eternal youth that the Moon Kingdom's ginzuishou could supposedly grant. She convinced the people of Earth to attack and destroy the Moon Kingdom, then retrieve the ginzuishou. They managed to kill Princess Serenity, her four guardian senshi, and their own Prince Endymion. Queen Serenity of the Moon Kingdom then used the last of her strength to employ the ginzuishou, sealing Metallia away within the Dark Kingdom, at Point D in the Arctic.

In the present day, Queen Beryl has been reincarnated on Earth, and breaks the seal to once again release Metallia. She lives in a stone castle beneath the Earth's surface. Metallia needs energy to fully reawaken, specifically the power of the ginzuishou. Queen Metallia's followers, after their reincarnation, are called together once again to take over the Earth.

After Sailor Moon kills Endymion and tries to kill herself, the ginzuishou forms a protective shield over the two. Metallia, sensing the presence of the ginzuishou, swallowed it, along with Endymion and Sailor Moon. Due to the power of the ginzuishou, she is released to the surface of the Earth and begins wreaking havoc all over the world. Sailor Moon reawakens within Metallia, and begins to cry. Her tears cause the ginzuishou to become a lotus shape, its true form. She attempts to use the power of the crystal against Metallia, but realizes she does not have the power to defeat the evil queen.

Mamoru, who had been told by Kunzite that Metallia's weak point was her heart, the marking on her forehead, told Sailor Moon to believe in herself because he would always be by her side. Sailor Moon then used the ginzuishou, the Moon Stick, and the power of the Sailor Senshi to hit the point on Metallia's forehead, destroying her. In the end of the manga, the Cauldron Guardian reveals that Metallia and all of the other major villains in BSSM were simply incantations of Chaos.

PGSM
Queen Metallia appears in Pretty Guardian Sailor Moon (美少女戦士セーラームーン, Bishōjo Senshi Sērā Mūn, often abbreviated to PGSM) is a Japanese tokusatsu television series based on the Sailor Moon media franchise. She is a very powerful entity that cannot be revived unless a great deal of energy is gathered. She is not fully awakened, and her awakening is the goal of the Dark Kingdom. It seems that she is Queen Beryl's boss. Kunzite seems to respect Queen Metallia more than Queen Beryl. Queen Metallia is first mentioned in act 16.

Trivia

 * The Negaforce is the only final antagonist to not be fought separately from the main antagonist. In Sailor Moon R, Diamond sacrifices himself to save Sailor Moon from Wiseman, who is defeated by Serena and Rini in the following episode. In Sailor Moon S, Germatoid is killed by Sailor Uranus, and in the following episode Hotaru overpowers Mistress 9, and later on in the episode Sailor Moon destroys Pharaoh 90. And in Sailor Moon Super S, Queen Nehelenia kills Zirconia and is fought in the next two episodes. As a matter of fact, Beryl and the Negaforce are one during the final battle, although many believe that the Negaforce was possessing Beryl.
 * The Negaforce is often compared to similar dark forms Wiseman and Pharaoh 90 from the next two seasons, R and S.
 * In the Sailor Moon manga, Metallia is a Chaos's form (the final enemy of the saga) and she's destroyed by Sailor Moon and she never combined with Queen Beryl.