The Santa Claus we now know, incorporating the older British Father Christmas and Lord of Misrule, presides over the period when order is upturned and merriment ensues. We can see some foundation in the Dutch Sinterklaas, who himself is derived from Saint Nicholas whose feast is marked on the 6th of December. 

https://www.patheos.com/blogs/bythepalemoonlight/2019/12/the-old-devil-saint-nick/