Spooky Ren Faire costume ideas?

My cousin (F21), sister (F23) and I (F21) are going to the renfaire for my cousins birthday on the 27th! (the halloween themed weekend) And as a lover of scary costumes I would love to dress up in something spooky-esque but accurate to the time period.

The problem is, i’m not too familiar with renaissance mythological creatures, legends, and other horror stories of the likes.

If anyone could help me out with any ideas I would greatly appreciate it! :D