1. Phantom Strikers - I have two descriptions. One a poem, and another a... description. I like the poem one better though, gives them a level of mysteriousness.
Banished from hell
We don't have a home
A recluse of all beings
The Phantom Strikers are
Into the shadows we stayed
Evading all other mortal life
Abhorred by the earth
We do not belong anywhere
They shall feel the pain
Legendary pain
They shall regret
Regret for forgetting us
The Phantom Strikers
---
Phantom Strikers, haakai in their native tongues, are once great demon lords in Hell banished by the archdevil himself, Mephisto (or Satan or Lucifer or Bob, whatever you guys call him/it/her). As they were banished, Mephisto (or whatever) drained all their powers, leaving themselves like their lesser kin. Although they were weakened, they were not dispirited. They found out that Mephisto only drained their energy level, not the power itself. They only needed for it to regenerate and evolve once again. They now live with the mortal beings in the world, trying to get along (or use them for their own gain), until the time has come for their revenge on the archdevil.
2. Oggeps
Oggeps are demon outcasts. Instead of the usual infernal power their kin have, they received the ability to heal and protect. This led to a mass racial discrimination against them. Fearing the eradication of their kind, the Oggeps fled to the mortal world and lived with the beings within it. The world's inhabitants, surprisingly, got along with them despite their still demonic appearance. Their magic capabilities evolved too, allowing them to massively heal a group back to peak performace, granting their allies with godlike strength, and eventually, bringing the dead back to life. Eventually, they developed features of the mortal races. Their scale-like skin faded, their horns became less apparent, their tails shorten to near unnotice. Sadly, that didn't happen to you.
3. Mages
A mage fancies himself (or herself) as an archdevil incarnate. They command a plethora of magical spells (elemental or arcane) that are only known to them. Reclusive even to their demon kin, some traversed to the mortal world to further improve their already impressive magical capabilities and shake off the usual nosy imp. Their spells can both be offensive (the usual fireball or the more showy Arcane Storm) or defensive (be it an armor of earth or a shield of pure magical force), likening or, in some instances, almost equaling themselves to their dark master.