All welcome to add to the list
Demi-Gods - Level 6 Class Units
Never more than 1 in a stack. Have the ability to gain experience and level up. Start out at level 1 similar strength as a level 5 class.
Djinn
A female djinn. A summoned unit like the Phoenix. The lower half of the body is a whirl wind. The unit is always in the air, so land based units can never attack it, can only be hit by archers and other flyers. Unit is able to cast a variety of unique non-offensive support magic. No attack capabilities. Units can move through and occupy the same space.
Night Hag
Access to recruit the unit is gained by a mid game quest that ends in traveling to the 'Gray Waste of Hades' similar fashion as Ultrax, finding and defeating a boss night hag in combat and after subjugating the hag solving a puzzle/quest given by the hag which is randomized from a pool of several possibilities. The Grey Waste map geography is randomly generated each game.
The Night Hag, a level 4 "animal" class. Has % chance of transmitting a unique disease "demon fever" when attacking by biting and clawing. Able to summon large quantities of weak unique level 1 demons called Larvae in the same fashion Demonologist's summon. For every 50 in a stack can summon 1 unique level 5 unit the Altraloth (1 of 4 different kinds appear randomly, Death, Pestilence, War, and Famine) charge 1. When attacking male humanoids small % chance that each one killed is mated with and produces 1 new night hag adding to the ranks up till the hero's leadership capacity. Gives +1 morale to demons level 4 or less with leadership less than total hag leadership. Single charge range limitless mind attack on a stack of evil units, if successful some % dies based on leadership of hags, those turn into Larvae on the spot that fight for the hero; persistence of mind resists. Low range magic attack like Demonologist.
Giants
Would like to see a whole race of Giants. Storm Giant, Hill Giant, Frost Giant, Fire Giant, Stone Giant, Cloud Giant.
Giant Types
Plants
Expand the plant units to become their own racial class. Lots of new magic specifically for plants including spells specifically to heal plants.
http://en.wikipedia.org/wiki/List_of_fictional_plants
Ki-Rin (magical and flying)
Chimera (attack type physical, magical & posion, but spread out over 3 areas, like phoenix attack. Flying. Unique special talent)
Manticore (Poison tail strike. Flying. Unique special talent)
Elementals (2 female / 2 male / 1 (astral) non-gender. air, water, fire, earth, astral. Summoned creatures)
Displacer Beast (enemy has % chance of missing due to displacer ability certain units immune to the displacer effect, bad morale with many other units countered by Voice of the Dragon skill, lots of action points, can target units up to 1 space away as normal attack, high damage, lvl.4 unit)
Doppelganger (unit is relatively weak in normal form. unit has talent where by a target is chosen and it becomes that unit type with abilities though retaining its own HP or something)
Lich (new level 4 class undead unit magician/warrior similar to shaman)
Rust Monster (when units with metal weapons attack it they lose some attack and/or damage rating each time they strike, when it strikes units with metal armor they lose some defense each time they are hit. Massively catastrophic to droids)
Wraith (new undead, a female wraith in the spirit of the demoness & dryad would be sweet)
Couatl (Level 5 class, much special magical talents)
Marilith (Level 5 class Demon)
Dragonne
So many possibilities:
http://en.wikipedia.org/wiki/List_of..._and_mythology
http://en.wikipedia.org/wiki/Category
ungeons_%26_Dragons_extraplanar_creature s
http://en.wikipedia.org/wiki/Magical_beast