Queen Neherenia

The Anime:

Neherenia is, of course, the leader of the Dead Moon. She only appears occassionally in mirrors throughout most of SS, only passing on orders to her underlings. You don't really get to see her in action till the very final episodes. When the Senshi defeat the Dead Moon Circus, Neherenia asks to be sealed behind mirrors so she can remain forever young and beautiful. However, this isn't the last we see of her. Neherenia has the distinction of being the only enemy in Sailormoon to appear in more than one season.

Neherenia traps each of the Senshi, except Usagi. In the end, Usagi frees her friends, and she "heals" Neherenia by returning her kindgom as a young princess before she was corrupted by the search for enternal beauty. Later it's revealed that Galaxia was responsible for awaking Neherenia. Galaxia somehow knew that Neherenia's return would also "awaken" Sailorsaturn within Hotaru which would cause her to age and become a Sailor Senshi once more. Galaxia wanted this so she could capture all of the Senshi Star Seeds.

Remember, Neherenia does not appear in the manga's version of SailorStars, only the anime's. The outers also appear in the last half of the manga version of SS while they do not appear at all in the anime. Actually the whole opening to SailorStars in the anime appears to be there so the anime can get closer to the manga story.

In the Manga Neherenia's main purpose is to get revenge for how she was treated by the Moon Kindgom during the Silver Millenium. It seems Neherenia was the Queen of a rival kingdom, also on the moon. When she went to the Moon Kingdom and refused to promise to be peaceful she was sealed inside a relm behind mirrors by Queen Serenity. In the manga, Neherenia is killed by Moon shortly after Neherenia finally gets her hands on the Golden Crystal.

Zirconia

The Anime:

Zirconia is ugly bug-like thing to the right. She is Neherenia's representative in "The Human Realm" and passes her orders on to the Amazon Trio and The Amazoness Quartet. Zirconia's constant companion is an eye with wings named Zircon. Zircon often appears with photos of the Circus' next victim or is used to keep an eye on the Trio and Quartet for Zirconia. When it's not flying around it perches on Zirconia's staff. Zirconia is killed off at the end of the anime.

In the manga, Zirconia turns out to be quite the powerful foe. Not only does Zirconia capture the quartet inside their magic balls, but also Chibi-moon and Saturn in some shards of glass from a mirror. She also at one point appears to kill the Senshi and Tux, but they only reappear in the "mirror relm". Luckily, Zirconia is killed off at the end of SS and we don't see her ugly mug again.