Diablo II/Enemies

Superior/Champion

 * Champions
 * Possessed

Zombies
Zombies >> Hungry Dead
 * Undead

Zombies are the second weakest enemy in the game, they are slow, they have a much higher maximum health than quill rats, and have a strong (again slow) melee attack. Unique zombies can sometimes be a hassle depending on their special traits, i.e. cold enchanted and extra strong can cause them to be over powered.

Quill Rats
Quill Rats >> Spiked Fiends >> Thorn Beasts >> Razor Spines

Fallen
Fallen >> Carvers >> Devilkin >> Dark Ones
 * Demon

Uniques

 * Rakanishu: Lightning Enchanted

Fallen Shaman
Fallen Shaman >> Carver Shaman
 * Demon, Raises dead of the same species (Fallen, Carver, etc.)

Gargantuan Beasts
Gargantuan Beasts >> Brutes

Gargantuan Beasts can be found in the Blood Moor, and Den of Evil. Brutes are found within the Black Marsh.

Uniques

 * Treehead Woodfist: Extra Strong, Extra Fast

Skeletons
Skeleton >> Returned
 * Undead

Uniques

 * Black Hawk
 * Puke Maw
 * Bone Drinker

Skeleton Archers
Skeleton Archers
 * Undead

Uniques

 * Dragon Jade The Jagged

Dark Rangers
Dark Ranger
 * Demon

Dark Hunters
Dark Hunter >> Vile Hunter
 * Demon

Vile Hunters are found in the Dark Wood.

Dark Spearwomen
Dark Spearwoman
 * Demon

Moon Clan (Goat Men)
Moon Clan >> Night Clan
 * Demon

Misshapen
Misshapen >> Tainted >> Plaguefiend
 * Demon

Special Uniques

 * Griswold: Undead, Cursed
 * Blood Raven
 * Andarial

Maggots
Sandworms >> Rockworms
 * Demon

Scarabs and Beetles
Scarabs/Death Beetles
 * Demon, Lightning Enchanted

Special Uniques

 * Radament
 * Coldworm the Burrower:Cold Enchanted, Magic Resistant, Immune to Cold
 * Duriel

Flayers
Flayers >> Undead Flayers >> Undead Soul Eaters?

Flayer Shaman
Flayer Shaman

Frogs
Frogs >> Slime Princes

Sextants
Sextants >> Cantors >> Heirophants

Special Uniques

 * Mephisto

Flesh Beasts
Flesh Beasts >> Stygian Hags

Flesh Spawners
Flesh Spawners >> Stygian Dogs

Special Uniques

 * Izual
 * Diablo