So I've been making a Tumblr blog of screencaps of background characters, trying to collect shots of the same character from different angles, when possible. (There's a few minor named characters in there too.) They're tagged by gender, age range, nationality, social class, and era.
I thought this might be useful for artists designing OCs, or even just new costumes for canon characters. It gives a good sense of the fashion, hairstyles, etc, of the world. Some of these might make good stock characters for fics too, or even obscure cosplay.
I only have caps from the first two eps up so far, but that's nearly thirty characters, and I plan to keep adding to it.
Avatar minor character designs