The Sailor Animamates were a group of Sailor Senshi who were minions of Sailor Galaxia. Their names follow a pattern, Sailor, usually followed by a [metal] and an [animal]
In the Manga, they were residents of their own home planet who killed their own planetary Sailor Senshi in order to gain Galaxia's favor. Sailor Galaxia sent Sailor Iron Mouse, Aluminum Siren, Lead Crow, and Tin Nyanko to Earth to retrieve Sailor Crystals. Iron Mouse failed, Aluminum Siren killed Sailor Mercury and Juptier before she herself was destroyed, Lead Crow killed Sailor Phobos and Demos before being destroyed and Tin Nyanko hurt Luna, Artemis, and Diana severly before Galaxia destroyed her for her failure. Sailor Heavy Metal Papillon tended the garden at Galaxia's base and attacked Sailor Moon and Sailor Kakyuu but was destroyed by Sailor Chibi Moon and the Sailor Quartet.
In the anime, the Sailor Animamates were used by Sailor Galaxia to search for true star seeds on Earth. They all wore bracelets which kept them alive, while they did not have star seeds of their own. They would use their bracelets to unlock the star seeds within people. If they were not true, the star seeds would be corrupted, turning the victim into a Phage, which obeyed them. They also used a telephone booth in order to travel. Galaxia first sent Sailor Iron Mouse, who had trouble locating true star seeds, and after a series of failures, Galaxia removed her bracelets, destroying her. Sailor Aluminum Siren and Lead Crow acted together as friends and partners, hunting star seeds. After a humiliating defeat for Aluminum Siren, having tried to steal Usagi's star seed after discovering she was Sailor Moon, Galaxia removed Aluminum Siren's bracelets, destroying her, and forced Lead Crow to work with Sailor Tin Nyanko. Lead Crow's new partnership with Tin Nyanko was more hostile than her partnership with Aluminum Siren. Eventually, Lead Crow figured out Sailor Moon's identity as Usagi through reading Aluminum Siren's diary, and she confronted Usagi, forcing her to submit by threatening to unleash a black hole. Lead Crow extracted the star seed, but before she could retrieve it, Tin Nyanko broke the container holding the black hole, unleashing it, and Lead Crow was destroyed, being sucked into it. Being unable to retieve Usagi's star seed, Tin Nyanko made a second attempt to steal it, but Sailor Moon was able to partially heal her, breaking one of the bracelets. Having grown annoyed with Tin Nyanko, Sailor Galaxia removed Tin Nyanko's last bracelet, destroying the last Sailor Animamate.
It is implied that they were once good Sailor Senshi, but were corrupted by Sailor Galaxia's power, had their Star Seeds removed, and became evil. This belief is reinforced when Sailor Moon was able to partially heal Sailor Tin Nyanko.