#1. His real name is Sinterklaas. And he is Dutch.
In the Low Countries (Netherlands, Belgium, Luxembourg) Sinterklaas is a traditional winter holiday figure and is where Western notions of "Santa Claus" originate from. He is also celebrated in former Dutch colonies like Indonesia and Aruba, and also answers to names like De Goedheiligman (The Good Holy Man) and De Sint (The Saint). In these countries he is celebrated on his name day December 5th, as the patron saint of children, sailors, and the city of Amsterdam.
#2. Before he became Santa, he was a bishop. And he saved prostitutes.
A 4th century Greek Christian bishop of Myra (in the Byzantine Empire, now Turkey), Saint Nicholas was a deeply religious man famous for his generous gifts to the poor. For instance, one time he presented the three impoverished daughters of a pious Christian with dowries so that they wouldn't have to become prostitutes. So the whole "naughty and nice" thing is a lot more literal than you realized.
#3. Actually, Santa was demoted from a god to a bishop during the Christianization of Germany.
Modern Christmas in the West is based on Yule, a Germanic midwinter religious festival. Yule time is connected to the Wild Hunt, a ghostly procession through the sky, of which the god Odin was the leader. The god Odin was known to have a long white beard, a hooded cloak, and ride his grey horse through the sky visiting the people with gifts. Pretty sure that's our Santa Claus, folks.
#4. Santa's blood type is AB+. Just kidding, he actually has goat blood because he used to be one.
Still working off this Yule celebration, in Scandinavia the bringer of presents was traditionally a goat, appropriately called the Yule Goat. That tradition is now extinct, but a straw goat is still a common Christmas decoration in all of Scandinavia. We have angels, they have goats.
#5. Santa's colour of choice is now red, but it used to be green. That's why traditional Western Christmas colours are red and green.
Original illustrations of modern-day Santa Claus portrayed him as a fat Dutch sailor with a pipe and a green coat. He was also seen in green in Charles Dickens' classic A Christmas Carol (1843) as the Ghost of Christmas Present, where he wears green robes lined with white fur.
#6. The story of Santa living at the North Pole can be traced back to Thomas Nast.
American cartoonist Thomas Nast published an illustration in Harper's Weekly in 1863 with the caption Santa Claussville, North Pole. Nast was also one of the first artists to define Santa's modern day image.
#7. Santa was married in 1889.
The idea of Mrs. Claus was popularized by American poet Katherine Lee Bates in 1889. Mrs. Claus resurfaced throughout the 1900s in children's books, poems, and songs.
#8. Before Coca-Cola, Santa had endorsement deals with White Rock Beverages, to sell mineral water and ginger ale.
Popular with Don Draper types everywhere, Santa has sold sugary beverages but also been used for charitable and benevolent purposes, most notably his campaigns with Salvation Army and other organizations for impoverished children and families.
#9. Santa is a very positive male icon.
"Santa is really the only cultural icon we have who's male, doesn't carry a gun, and is all about peace, joy, giving, and caring for other people. That's part of the magic for me, especially in a culture where we've become so commercialized and hooked into manufactured icons. Santa is much more organic, integral, connected to the past, and therefore connected to the future." - TV producer Jonathan Meath, 2011
#10. Underneath that cute chubby cheerful exterior, however, Santa might be letting the riches getting to him.
Santa Claus has been placed by the Fictional Forbes 15 as the richest character in the world, with a net worth of ∞ in 2002 and a net worth of "excessive" (in $billion) in 2005.
According to Forbes, he has been called out for blocking elves from unionizing and for forcing elves to work in hazardous working conditions. His large elvish work-force makes an estimated 700 million toys worth ~14 billion US dollars. They are subject to working in perpetual darkness for over half the year in the Arctic Circle.
Warner Flackmout maintains that, "this has been going on for hundreds of years. The industry has a long-standing relationship with Mr. Claus. As long as he confines his philanthropic activities to one day out of the year, we are happy to look the other way. But if he were to expand his operations—say start giving away toys on midsummer’s night eve or something—we would have a problem on our hands." The Fictional Forbes team fears that he may be flooding the market with cheap toys given his innumerable wealth.