If you're looking for a great Halloween costume I have to say this Headless Horseman is definitely up there! And with the success of the television series "Sleepy Hollow" it's quite timely.
It comes in lots of different sizes, so anyone can wear this costume. Well, I wouldn't recommend it for toddlers, but children in elementary school (if they're not too scared) could get one to fit.
Note, the children's sizes seem to run small, so get one size larger.