Tier 1.
Peasant Raiders: Peasants whom are lightly armed and who's main specialty is looting and robbing. Not very dependable

... (Current Rhudar Spearmen, with few modifications)
Goblin Slaves: These unfortunate creatures are slaves to the chiefs of Angmar. Their major job in life is to his bidding and earn their meat. (Snaga with Shield and Axe/Blade)
Goblin Archers: Same as above, only specialty is with the bow.
Mountain Hunters: These barbaric fellows spend almost all of their time away from the "Civilization" they know. Living off what they can kill with their primative spears. They have become as wild as the creatures they devour (Light units with throwing Javellins and uses a hunting knife for melee)...
Tier 2
Warriors of the North: These are the "Professionals" of the Northern Armies. Their reknown for their ferocity, that is even been known to surpass that of the Orc. (Warriors with helmet, fur coat, cape, handaxe/swords with a buckler. I have a model in mind

)...
Axethrowers of Angmar: These men are experts at tossing their metal...
The Vultures: These Orcs are probably some of the most fiersom in battle, this is probably due to the fact of the harsh environment they live in. Very versitile in combat...
Northern Wolves: The lands of Eriador and the North have always been plagged with wolves. These creatures are far more majestic and reasonable than their mutated Warg cousins. Their alliance with Angmar is age old (Do I even need to say

)
Village Strongmen: These are the "Fists" of the chieftains, they collect his taxes and keep the people in order, and he rewards them with booze, woman, and just about anything they wish... (Armorerd in Chain Overcoat, and armed with a two handed axe/club/mace/etc... Have model inmind

)
Mounted Warriors: Horses are rare in the North, but not extinct. Most Warriors prefer to fight on foot. But their are a few who have mastered the art of mounted combat.... (Mounted Warriors lol)
Mountain trolls
Tier 3
Warrior-Priests of Melkor: These are the religious heads who keep the people in line. The delve into the deep arts and their presence encourages the armies on the battlefield... (Robed freaks with bladed staves, can chant and encourage friendlies while discouraging enemies)
Gaurdians of Carn Dum: Wildest of Berserkers who claim they are descendants of the first Beserkers who served under the Witch King. Their Fury is unmatched, and they are said to even frighten the Dunedain
Warg-Riders of Gundabad: Orcs who have formed alliances with the Northern Wargs. They ride on their backs, armed with recurve bows and large blades. This is a dangerous alliance..... (I just said it

)
Snow Trolls
War-Chiefs Kinsmen: These are the closest relatives to the Chiefs. They have immense loyalty and serve as his bodygaurd. They wield Swords that are still red from the furnaces of Angmar.. (Well Chain Armored heavy infantry units with Hefty Shields and Swords to Match)