What am I looking at here?

[Bri5]

I can't give a lot of details because I don't have many. Approximately 6 months, recently fixed and vaccinated, cat that was indoor/outdoor with a cat hoarder.

 

[Caspers Human]

My guess is either mange or scabies.
Although the root cause is different, there's some overlap between the two. In fact, some people call them the same thing.

Either way, a trip to the vet is in order. Given proper treatment, you should be able to clear this up in a reasonable time.