Backgrounder

Backgrounder is old fandom slang for the background characters in each episode. Some of these, mainly by accident, have names (like through a seating chart in "Cafe Disaffecto") but they almost all lack a voice - and if they have names, our main cast never refer to them.

They are extremely useful for fanfic writers: a source of ready-made people with an existing image, that your fellow obsessives may know!