The NPC in World of Warcraft refers to "Non-Player Character" controlled by Computer. They do not take part in the battle for WOW Leveling and just give you a direction on game guide, especially on WoW Powerleveling. The NPC includes questgivers, vendors, guards, bankers, and trainers are all considered NPCs to help you with World of Warcraft Leveling. Some NPCs are neutral to all races who need WOW Power leveling while some are just available to certain faction.

You cannot attack NPCs and shopkeepers in your own faction when you are WOW Leveling. However, you can attack NPCs and shopkeepers from the opposing side to enhance your WoW Powerleveling, as well as some neutral NPCs. Many neutral NPCs that are useful for your WOW Leveling are affiliated with a particular reputation, such as the Argent Dawn NPCs. You must be "at war" with a group (found in the Reputations tab of your character sheet) in order to attack their NPCs to enhance your World of Warcraft Leveling.

You should remember that the opposite NPCs reside in the opposite factions’ city and town during the process of WOW Leveling. If you attack a NPC or shopkeeper on normal realms when you are WoW Powerleveling, you will be flagged and enemy players may attack you during the process of WOW Power leveling. Players may attack you on PvP realms once you enter the towns and cities. However, it is a memorable accomplishment once you defeat a prominent NPC when you are World of Warcraft Leveling such as a racial leader.