Instead of pumpkins and witches, I've decided to do a rural take on the subject.
The 'Santa Compaña' (Holy Company) is a mytical belief from Galicia and Asturias (my land, where it is called "Güestia"), in northwest Spain. It's a procession of souls that wanders paths and forests. It's an omen of death for those who see it pass by.
It's said that if you see the Santa Compaña you must draw a circle in the ground and get in, or lie face-down and cover your ears to not hear their prayers.
And never ever accept a candle if it's handled to you by one of these souls or you'll be soon joining the company.