Most important NPCS are in the FM.
Here is the list
Coco = Fame seller
Cody = Job advancer
Mia = Tell u the GM list
Ueriba = PVP Warper
Duey = Scroll Seller
Mysterious Statue = Map Warper
Amos the strong = Boss warper
O Pongo = Skill Buff NPC
Metorite 2 = Meso to Item Converter(leafs)
Spindle = NX seller
Mr Oh = All in one seller
Shanks = All in one npc
Harry = Event Manager
Sera = Stats Reseter
Pachinko 2 = JukeBox
KIN = Skin,Hair,Eye Changer For males
NimaKIN = Skin,Hair,Eye Change For Females
Metorite 3 = Warps u to Boss Spawn Map or Southperry