Ptilol

Ptilol (Petite Roll in the manga and Petirol in the dub) and Cyprine are, together, considered the fifth of the Witches 5. It has been stated by Naoko Takeuchi in the Materials Collection that Ptilol is just an extension of Cyprine's power, yet they seem to act as one. Ptilol is named for the mineral ptilolite.
Ptilol is simply the other half of the witch Cyprine.
In the anime, Cyprine was portrayed as the last of the Witches 5. It was only when confronted that she revealed her "other self", Ptilol. The two prove nearly invincible to the Sailor Senshi, as one always blocks incoming attacks with her powers while the other blasts from behind. Gradually, the Senshi are able to trick the two into blasting each other, killing both at the same time.
In the manga, Cyprine is the highest ranking witch at level 999, and her death attack is "Ribbon Buster." She was called upon by Kaolinite specifically to take care of the Sailor Senshi. Cyprine attacks Haruka Tenoh in her apartment. Haruka promptly transforms into Sailor Uranus, and the Inner Senshi, Sailor Neptune and Sailor Pluto appear to aid their fellow senshi. Cyprine then uses her power to magnify the preexisting feelings of hostility and tension between the Inner Senshi and Outer Senshi. Sailor Moon, horrified by the maneuver, attempts to destroy Cyprine with her Moon Spiral Heart Attack, but this attack fails. Cyprine isn't hurt, and instead splits herself into two halves, herself and another, Ptilol. These two are only one person, split in two, and are not twins. Cyprine is the only fifth witch, and Ptilol is merely an extension of Cyprine that has to manifested itself as Ptilol. Cyprine and Ptilol are one, and they believe that no one can defeat them. Sailor Moon gathers energy from all of the senshi to create the Holy Grail, and uses it to transform into Super Sailor Moon. She then uses her "Rainbow Moon Heart Ache" attack to destroy Cyprine and Ptilol.