Atronachs

(Armor 6, Health 25 to 140, Damage 5-15)

Four major varieties: Flesh, Iron, Ice and Fire (I seem to recall running into Water and Air, too, but I could be mistaken). Medium to light hitters, lots of hits points, and no treasure. They’re about on par with the zombie. Their defense lies in their restistance to certain types of spells.  Fire-based spells will heal a Fire Atronach, Electricity will heal an Iron Atronach, Poison/Acid will heal a Flesh Atronach, Frost will heal an Ice Atronach. They aren't immune from a good weapon strike, though. If you want money off these guys, pick their pockets before you kill them.

Gargoyles

(Armor 0, Health 19 to 82; Damage 10-15)

Gargoyles don't carry any treasure and have no special attacks. You usually don't start running into them until you're about 7th level. You need Mithril weapons or better to hit them.