The Lucavi

The Lucavi are a group of demons based around the signs of the Zodiac. Their primary goal seems to be to resurrect their master, Altima, possessing the body of St. Ajora. Hashmalum seems to be some sort of consigliere to Altima, as he is the puppeteer for much of the game's action prior to her resurrection. The Lucavi are written to be the saviors of Ivalice, immortal, all-powerful gods, but as Ramza and his troupe travel through the game, they discover this is not the case. Fearsome though they may be, they are also mortal, and can be killed, especially since the writings say there were twelve originally, though after over a millennium, only six remain (and a secret, optional boss).

The Zodiac signs of Aquarius, Cancer, Libra, Pisces, Sagittarius, and Taurus do not have respective Lucavi Demons as far as we know. Either they never existed or were slain prior to the timeline of the game.