Forums of the Megaverse®

Dedicated & Worldly Martial Artists (N&SS)
Mystic Bestowal, Ancient Master and Stage Magician (HU2)
Burster (Rifts)
True Atlantean Nomad (Atlantis)
Ocean Mage, Sea Druid and Whale Singer (Rifts Undeseas)
Psi-Warrior, Psi-nullifier and psi-druid (Psyscape)

Mutant animals from AtB too

Some of the aliens in Aliens Unlimited might be fun to adapt to a fantasy setting, too.

And, obviously, I would tone down the OCCs/RCCs as needed.

Depends on the campaign.

If you're doing a high-power campaign:
Dragon Hatchlings
Demi-Gods (I'm kinda leery of Godlings)
Pretty much any magic, super-powered or psionic-based RCC or OCC that's high up on the power end from HU, Rifts, and the rest of the megaverse


If you're doing a medium-power (champion-hero type) campaign:
Martial Artists
Magic and psionic-using OCC's from Rifts: England, Mystic Russia, and perhaps some others.

For low-powered (ordinary people in extraordinary events) campaigns:
The Vagabond (minus any modern skills and gear)
That's about it.

Lots of the stuff in Trans Dimentional TMNT, Temporal mage (time lord?).

Shifter
Temporal Wizard
Conjurer
Possibably a Battle Magus
Mystic Knight
Dogboys(R.C.C but usable)
Psi Stalkers
Mind Bleeder
Psi- Druid
Psi-Warrior
Burster
Naga Psychic(Psyscapes vertion)
Tribal Warrior
Mystic Warrior
Totem Warrior
Spirit Warrior
Plant Shaman
Animal Shaman
Mask Shaman
Healing Shaman
Paradox Shaman
Fetish Shaman
Ocean Wizard
Sea Druid
True Samurai
Ronin(Personal Fav)
Mystic Ninja
Yamabushi Mountain Priest
Demon Queller

Chamalkan, I'd allow anything you could come up with a plausable explanation for...