* The Arachnid Quarter
Anub'Rekhan: A beetle-like Nerubian Crypt Lord.
Grand Widow Faerlina: High ranking Cult-mistress of the Cult of the Damned.
Maexxna: A colossal highly poisonous Spider.
* The Plague Quarter
Noth the Plaguebringer: A Necromancer specialized in curses and summoning.
Heigan the Unclean: A Necromancer specialized in diseases and dancing.
Loatheb: A giant Fungal Monster.
* The Military Quarter
Instructor Razuvious: The Death Knight trainer of Naxxramas.
Gothik the Harvester: Grand Necromancer of the Lich King and the legions he commands.
The Four Horsemen: Four mounted high ranking Death Knight bosses at once.
* The Construct Quarter
Patchwerk: A titanic standard Abomination.
Grobbulus: A slime based Abomination.
Gluth: An Abomination-Dog created from animal parts.
Thaddius: A massive abomination with electricity based powers.
* Frostwyrm Lair
Sapphiron, a gigantic frost wyrm.
The dread Archlich Kel'Thuzad, second in command to the Lich King.