Off the top of my head...
-NPCs are most commonly found in the various adventures, but those tend to be specific to that adventure.
-Some (but not most) of the setting books have NPCs statted out. Glorious Empire, for example, has stats for both named figures (Grand Emperor Krial) and more general but still region specific npcs (Slave Laborer). Clans of the Aslan is another good one for this.
- There's also several JTAS volumes which feature statted and storied NPCs.
- Honestly I think your best bet is going to be the Bounty Hunter book, which features 21 named and storied bounty hunter types and 14 generic stat blocks for criminal types (Crime Boss, Drug Dealer, Gambler) that the travellers might encounter.
Does that help?
(Edit: Oh, and there's a few in the robot book for robots that are basically NPCs)