NPC means Non-playing-characters
These are characters you may meet in the LARP that are not normal players. They are sent by the organizer.
An NPC is usually in the game to make the story/intrigue better. To make things happen. They may be in the game for a short time (a few hours) and their character history may not be so deep.
Remember; NPC players are still players that want to have fun, so take them seriously and be careful with them. Sometimes they have fighting roles, but may not be so used to fighting, so try to “read” their limits and capabilities.
If you want to be an NPC you can ask the organizer.
The organizer usually has costumes for the NPC and if they are skilled and “work” the full shift – they are usually not asked to pay any participation fee. For really experienced players the NPC role can offer important roles that can carry lots of “story”.
NPC players may be asked to play lots of different roles. It is also possible that an NPC player will only play one or two roles. As a general rule the NPC players will play robber tribes, slaves or sacrifices during the day and then something mighty and powerful during the night. However the dayrole could also be something like an entertainer, trader, soldier or even a King or a Queen and the nightrole could be something like a slave or a sacrifice – so NPC players must be ready for low status roles.