Boatman
TESA: Redguard
Bonelord
TES3: Morrowind
Boneman
TESL: Battlespire
Bonewalker
TES3: Morrowind
Bonewolf
TES3: Bloodmoon
Draugr
TES3: Bloodmoon
Dwarven Specter
TES3: Morrowind
Ghost
TES1: Arena, TES2: Daggerfall, TESL: Battlespire, TES3: Morrowind (as Ancestor Ghost), TES4: Oblivion (Ghost, Ancient Ghost)
Ghoul
TES1: Arena
From the manual:
These undead are the carrion eaters of dungeons, crypts, and other burial places. They feast on human corpses and other rotting flesh. Although they are not intelligent, they have a natural cunning that aids them in finding food. Because of their vile habits, ghouls have a chance of transmitting a disease to those they bite.
Ideal Master
TESL: Battlespire
Lich
TES1: Arena, TES2: Daggerfall (Lich, Ancient Lich), TES3: Tribunal, TES4: Oblivion (Lich, Nether Lich)
Mistman
TESL: Battlespire
Mummy
TES2: Daggerfall
Shambles
TES4: Shivering Isles
A collection of random bones held together with wire or cloth. They are resistant to all frost magic, and unleash a powerful burst of frost when killed.
Skeleton
TES1: Arena, TES2: Daggerfall, TESL: Battlespire, TES3: Morrowind, TES4: Oblivion
A classic creature, found in most TES games. In Arena, they are described as:
undead creatures, once human, now animated by some forces either magical or supernatural. They usually are set to guard certain places, such as burial crypts or vaults. They have a single minded purpose, and will track their foes until the hapless victim is found and destroyed.
In Morrowind, skeletons are the result of the ritual necromancy of the Dunmer, and serve to guard their tombs. In Oblivion, they are often found in Necromancer lairs.
In Arena, Skeletons cannot be harmed by edged weapons. In the later games, only a silver or better weapon can do damage.
Skinned Hound
TES4: Shivering Isles
A powerfully undead adversary with a weakness to fire. It is not intelligent, but, according to Namlir, has an "insatiable hunger for flesh."
Wraith
TES1: Arena, TES2: Daggerfall, TESL: Battlespire (Wraith, Wrathman Wraith), TES4: Oblivion (Wraith, Faded Wraith, Gloom Wraith)
Zombie
TES1: Arena, TES2: Daggerfall, TESA: Redguard, TES4: Oblivion (Zombie, Dread Zombie, Headless Zombie)
Creatures that have already been dead once. Often require a special rank weapon to be harmed.