The Dark Kingdom

The Dark Kingdom were the villains of the first season of Sailormoon.  Queen Metallia was the main leader, and Queen Beryl was her servant.  Beryl had four servants herself: Jadeite, Nephrite, Zoicite, and Kunzite.  They collected energy for Beryl, which Beryl gave to Metallia.  They were also looking for the Ginzuishou.
Queen Beryl
Beryl is the main servant of Queen Metallia, who is the queen of the Dark Kingdom.  She wants revenge on Usagi, because when Usagi was Princess Serenity, Prince Endymion loved her.  Beryl loved Endymion, though, so she was jealous.  And she also wants the ginzuishou, which Usagi has, so that she can rule the universe.  Beryl is not very patient nor tolerant with her henchmen.  She doesn't tolerate failure, mistakes, or anything like that from her generals.  She practically demands that they worship her, and if they don't she just gets rid of them, no questions asked.  She's sort of powerful, especially with that power staff thing that she always has.  But when she is possessed by Queen Metallia, she becomes a lot more powerful.  Once all her generals except Kunzite are either dead or in eternal sleep, she kidnaps Mamoru and turns him into Prince Endymion again, erasing his memories in the process.  Then during the final battle between the senshi and Beryl, Usagi returns Mamoru's memories and he wounds Beryl with his roses (possibly she's weaker than we thought?).  She's, like, dying so she goes to Metallia and Metallia fuses with her and Metallia/Beryl is eventually defeated by the ginzuishou.

Jadeite is the first of Beryl's generals.  He is sent to Earth to collect energy from humans, which Beryl fed to Queen Metallia.  He usually would collect energy from a large crowd, and then channel it back to the Dark Kingdom through an object, like a clock, a disco ball, a flower, jewelry, or any other object.  He collects energy using three of the deadly sins: greed, vanity, and gluttony.  He also collects energy from people who are experiencing other extremes, such as fame, pride, panic, scholastic achievement, but mostly love or excitement.  He'll manipulate people so that they'll reach those extremes, then he'll steal their energy.  Jadeite is good at illusions and disguises.  He had disguised himself as a radio host, an aerobics teacher, a caretaker at Rei's shrine, a security guard, and a captain of a cruise ship (he actually changed his hair color for that one).  At first he goes by the name J. Daito, and that's how Usagi learns his name.  He also turned a derelict, wrecked ship into a cruise liner; and projected an image of himself over Tokyo and made it look like the city was on fire to threaten Usagi.  He learned the identity of Mercury, Mars, and Moon, but then before he could tell Beryl, she sealed him in a giant crystal and put him into eternal sleep.

Neffy's hair looks like mine kinda...
Nephrite was Beryl's second general, who replaced Jadeite after he was done away with.  His mission was the same as Jadeite's at first: collect energy.  What he would do was he would find a human whose energy was at its maximum peak.  He would almost always ask the stars for guidance, and he would ask the constellations which human's energy he should use (he would be a good astrologer).  Then once he had found that human (usually it was a human with a particular talent, such as tennis or photography), he would take an item that they used and infest it with a youma (and his youma symbol, which is a stylized "ne" katakana (the first katakana of his name) would appear on the object).  Then when they used that object a lot, their energy would rise to its peak, then Nephrite would turn the object into a youma and have the youma steal the person's energy.  Then later, he's supposed to find the ginzuishou.  He uses a crystal to help him find it, and he also asked Osaka Naru (who was in love with him) to find it for him.  But Nephrite ended up falling in love with Naru, and Zoicite thought he was being a traitor and so he sent his youma to kill Nephrite.

Zoicite is a MAN, for those who don't know...
Zoicite is the third general of Queen Beryl, and his mission was to get the nijizuishou, or the rainbow crystals; and then to get the ginzuishou.  He was trained by Kunzite, but they're more than just friends, they also have a romantic relationship.  His rival is Nephrite, and Zoicite always criticizes him.  Zoicite is also very disrespectful and also ambitious, willing to do anything to prove himself to Kunzite.  He's also vain, sneaky, and manipulative.  He sometimes will threaten Sailormoon or Tuxedo Kamen that if they don't do what he says that he'll hurt some innocent human or whatnot.  He doesn't ever fight unless he's sure he'll win, and if he's halfway through a fight he'll just teleport away so as not to get beaten up.  His powers include levitation, telekinesis, illusions, and forming crystal daggers or sakura blossoms (flowers from cherry trees).  The sakura also appear when he teleports anywhere, and he uses them to distract people in battle.  He has also disguised himself as Sailormoon in order to lure Tuxedo Kamen into his trap, and he looked a lot like her except his eyes were the wrong shape (though there's really nothing he could do about that, is there?), and where her fuku was supposed to be red his was purple.  Another thing that he has done was somehow project his image on Mamoru's TV and send threatening messages to him.  He disobeyed a direct order from Queen Beryl, so she killed him and he died in Kunzite's arms.
I don't see why everyone likes Kunzite so much...
Kunzite is Beryl's fourth and last general, probably the most powerful.  He is able to do telekinesis, teleportation, levitation, project his image, make explosions, throw around energy boomerangs, and create a dome that he once trapped the senshi in.  But his main attacks are a stream of energy, black energy globes, or the boomerang things.  Kunzite was supposed to teach Prince Endymion, and he also taught Zoicite.  Although he disliked Endymion and liked to see him fail, he seemed to have confidence that Zoicite would succeed, but warned Zoicite to not disobey the queen or else.  He is a cunning warrior, and doesn't fight without a plan.  He really cared for Zoicite though, and even though he pleaded with Beryl to spare his life, in the end Zoicite still died.  Kunzite died too, when he attacked Sailormoon but she deflected it back to him and it killed him.