The following assorted minions of evil make very brief appearances; we have only the barest glimpse of them, and not a clue as to their characters. Still, I didn't want to neglect them...
The droids of the Black Moon are featureless creatures that can disguise themselves as ordinary human beings. Their function was to aid the Ayakashi sisters in their tasks. Their disguise cut into the senshi's effectiveness, because the girls are reluctant to hurt innocent bystanders. Sailormars was the first to figure out that the droids wore human guise; at the T-A Private Girls' School, they disguised themselves as nuns. Afterwards, the girls were able to figure out that overly vicious "people" were probably Black Moon droids.
Each droid has a blank round face, with eyes closed to slits, and an upside-down black crescent on their foreheads. Their bodies are completely black-clad, with odd shoulder spikes. Safire manufactures them, and then infuses them with a fraction of life-essence from the Evil Black Crystal.
Kiral and Akiral, the Bull Brothers, answer to Esmeraude. At her command, they attempted to capture Sailormoon. (They failed, which is why she had to do it.) Kiral is the light-skinned one, and Akiral has dark skin. They are tall, slender, and wear the Black Moon on their foreheads.
Akiral has the power to create several images of himself; he also surrounded the senshi with a crystal wall of electricity. (As Kiral pointed out, the magnetic field inside the wall nullified their powers. Don't ask me how they managed that, I don't know...) Their power is apparently to create a huge chemical reaction that would have destroyed the senshi. However, Tuxedo Kamen and Sailorvenus manage to break free; their attacks killed the Bull Brothers.
...uh, oops. Ian Miller has informed me that "Achiral and Chiral are the Boule Brothers and not the "Bull Brothers." The term "boule" is used in crystallography." (ilsevet: a "boule" is a pear-shaped synthetically formed mass (as of sapphire) with the atomic structure of a single crystal. Thank you, Merriam Webster!)
Veneti and Aquatiki are the shadowy servants of Safire; they collect energy to help him manufacture droids. They have no shape; their bodies are like wisps of smoke. Heads and chests are given a rough approximation; the rest of the body does not seem to be evident.
At any rate, Safire was talking to them when Usagi walked in. Upon Safire's orders, Veneti and Aquatiki threw themselves at Usagi, knocking her down onto the ground. Safire then made an abortive attempt to kill Usagi, but she transformed into Sailormoon and started wreaking havoc.
It's not shown that Sailormoon actually killed Veneti and Aquatiki, but I assume that she did. Sailormoon is a good fighter, and doesn't usually leave loose ends lying about.