Perchta the Hidden One

The season of Yule is better known as Christmas to the vast majority of people. It's also called the Winter Solstice period, when some just worship the movements of the sun and look at the seasons changing as a divine thing. Many pre-Christian and pagan beliefs celebrate this time as a season of both the Winter Solstice and the birth of the new gods. It can be celebrated in many ways, or be a time when people called out for the sun to please come back. There are many forgotten pieces of Yuletide that I want to touch on without going into too much heavy research. There is a lost celebration or tradition in the December/Winter period that honours the Light Goddess.
In ancient lands now Germany, France, Netherlands, Austria, Britain, Channel Islands, ect people understood that it was a time of the goddess of the sun, warmth, fire and the light. She was called "The Hidden One". Her name is Perchta or Bertha, depending on where she was found. Sometimes she resembled an old woman, and other times a beautiful snow-white maiden. Linked with spinning and weaving, and swans, snow and winter sunlight, this mysterious hidden goddess spends most of the year inside dark forests and caves. She emerges in Winter.
This goddess is said to watch over children in Winter and check to see if they've been well behaved. The notion that kids will get presents from Santa if they've been good, come from this belief in the Hidden Goddess, she watches people. Now most modern parents have started a new Winter trend of using toys or "Elf on the Shelf" to monitor children and how they behave. The idea of watching children being good or naughty derives from the centuries old tradition of people of most households telling kids to "mind how they behave" because "Perchta is watching them".
If children as well as servants have been well behaved, she'll reward them with money, food, gifts and even clothes. If not, and people have been bad, she was said to cut people open and fill them with pebbles as a form of punishment. This hidden goddess was feared because she was cruel if anyone stepped out of line and resorted to badness. She cared about people enough to study how they worked, to find out what people ate on certain days and to see how they acted towards others. She didn't want people to offend her. She stuffed people with straw if they didn't eat the proper food on certain feast days. Foods that people should eat are fish and gruel. Anything else was said to be a great offense. Her days were the twelves days and she was part of Winter time. 
Today you'll find celebrations of the hidden goddess of Winter. It's called Perchtenlaufen. People in Austria recognise this and regard Perchta as a "witch" who appears after midwinter in January who tortures people. Many on this festival wear creepy and scary monstrous masks to scare away Perchta.
She's linked to the Wild Hunt and associated with the Norse goddess Frigga. It was the goddess Frigga who originally gave presents to children and poor people in ancient times during the Winter season. It was said that Mother's Night is based upon the coming of Frigga and the goddess of maternal love. In Winter, children who were afraid of the cold, dark and threats of predators, hunger and illness, sought the comfort of the loving and nurturing goddess when their own mothers were poorly, dead, or just suffering as anyone else. It seems likely that the church demonised Perchta and made her into an "ugly witch" that cuts people for being naughty. Like with all goddess worship, the church has demonised plenty other goddess, gods and divine animals. However, the ancient and primitive beliefs that all went with the arrival of Perchta, the Hidden One, remains there to this day. Now it is transformed into Santa and his elves, the christmas tree fairy and the ice maidens in pretty clothes found in Russia (Snegurochka) and Disney (Elsa and Periwinkle).

Links:
Frau Perchta the Terrifying Christmas Witch
The art above is by Anne Stokes