Samhain (October or November)
Samhain was a festival celebrated by Celtic peoples at the end of the harvest season. Some of the practices of this ancient holiday were adopted as part of Western Halloween. Celts honored spirits of ancestors during that day, with skull and bone decorations and fires (this eventually evolved into costumes and jack-o-lanterns).
There has been a movement in modern times to reinvent Samhain as a kind of neo-pagan new year. Samhain was one of four end-of-season Celtic celebrations, but famed anthropologist James George Frazer popularized the idea that the holiday was a kind of new year for ancient Celts. Despite his theory, he admitted that the evidence was inconclusive. Many Neo-Pagan groups have adopted the holiday as their new year nonetheless. They celebrate in different ways, with bonfires, dancing, the placing of shrines and other rituals inspired by practices dating back to ancient times.