13,394 NPCs

Classic reference; current Forever availability is unconfirmed.

NPCLevelTitleZone
Auctioneer Silva'las50Darnassus
Auctioneer Cazarez50Darnassus
Auctioneer O'reely50Stranglethorn Vale
Auctioneer Cain50Undercity
Auctioneer Naxxremis50Undercity
Auctioneer Tricket50Undercity
Southsea Kidnapper45Tanaris
Auctioneer Rhyker50Undercity
Dark Iron Kidnapper42–45Searing Gorge
Jonathan the Revelator61Silithus
Stormwind Reveler1–60Moonglade
War Effort Recruit30Orgrimmar
Warlord Gorchuk60War Effort CommanderOrgrimmar
Field Marshal Snowfall60War Effort CommanderIronforge
Senior Sergeant Taiga60War Effort RecruiterThunder Bluff
Senior Sergeant Grimsford60War Effort RecruiterUndercity
Senior Sergeant Kai'jin60War Effort RecruiterOrgrimmar
Master Sergeant Fizzlebolt60War Effort RecruiterIronforge
Master Sergeant Maclure60War Effort RecruiterStormwind City
Master Sergeant Moonshadow60War Effort RecruiterDarnassus
Dirt Mound60Eastern Plaguelands
Thunder Bluff Reveler1Moonglade
Squire Leoren Mal'derath60Stable MasterSilithus
C'Thun63Ahn'Qiraj
Pat's Snowcloud Guy60Wetlands
Darnassus Commendation Officer55Ironforge
Wonderform Operator30Smokywood PasturesStormwind City
Gnomeregan Commendation Officer55Ironforge
Ironforge Commendation Officer55Ironforge
Stormwind Commendation Officer55Ironforge
Orgrimmar Commendation Officer55Orgrimmar
Darkspear Commendation Officer55Orgrimmar
Undercity Commendation Officer55Orgrimmar
Thunder Bluff Commendation Officer55Orgrimmar
Colossal Anubisath Warbringer63
Imperial Qiraji Destroyer62–63
Qiraji Captain35
Lesser Anubisath Warbringer33–35
Lesser Silithid Flayer30–31
Qiraji Major45–48

Classic reference data from QuestieDB (Forever data, commit c5de61a), with positions on Forever's zone maps. It doesn't confirm that an NPC, location, quest or item is in Forever.