Diablo II/Enemies

Zombies
Zombies >> Hungry Dead

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

Forsaken
Forskane >> Carvers >> Devilkin >> Dark Ones

Dark Hunters
Dark Hunters >> Dark Spearwomen

Tainted
Tainted >> Plaguefiend

Special Uniques

 * Blood Raven
 * Andarial

Special Uniques

 * Duriel

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

Flayer Shaman
Flayer Shaman

Frogs
Frogs >> Slime Princes

Sextants
Sextants >> Cantors >> Heirophants

Special Uniques

 * Mephisto

Special Uniques

 * Izual
 * Diablo