Does anyone know Neville's patronus?

It has never been revealed, in the books, 映画 または によって JK herself :)

hm. it doesn't say so in the 本 または movies, and his just disappears without forming completely. jo herself hasn't revealed it either. but i would expect it to be a badger, toad, tiger, または some other animal that represents him.
~potternerd~

I know for a fact he can produce a corporeal Patronus. あなた see it in OOTP. It bursts from his wand, making him stagger, and trips Ron. From what I could see and hear, it is a canid of some kind.