Behind the butcher in Strawberry is a man with a lot of leather curing and tanning supplies, including racks and such. He's never had any mechanical purpose, but Callum always goes to him when he needs hides cured or tanned (at least in 1.0 since I haven't been able to do much hunting since), since I figure him as a professional trapper/tanner. Callum's always referred to him as "Guillaume", and I imagined he came from the northern states or even Canada.
He typically offers his services at a small charge, but likes to know the story behind each pelt and how his customers intend to use them. I imagine he's somewhat withdrawn, which works since Callum is typically reclusive when he goes hunting.
Mountain Medical also has a few "invisible" NPCs working throughout the state to help administer ongoing care with comatose patients and such. They don't really fit with the rest of the thread, since they are exclusively "lore NPCs", but they still play a big role for us. The most prominent among them, and the one that I think a decent people outside of MM know, is "Nurse Nora" who operates out of the St. Denis Ward. She's a tough cookie, pretty stern when it comes to patient care, and is also a massive coffee fiend.
I believe Jaena Shaw is the one to credit with her lore establishment, and she's been providing aid to longer term patients ever since.