I have one incoming anthro for whom I'll be making a mad scientist costume. Which is just a lab coat basically. He'll prolly wear it all the time though so it's not much of a costume. For my DOT Sha, I made a big bad wolf costume with the remains of a wolf plushie from the thrift store. Just take out the stuffing, cut and attach a zipper and BAM! Big Bad Wolf. Wish I still had it
Hmmm, well I have a Pure Neemo (M sized?) witch costume and and a few Obitsu 25 cm girls with not much else to do. Maybe I should put something together.
For that matter, I don't know if most of my primary cast even celebrates Halloween.