Who is this jolly gift giver really? Here is the the history behind him, according to www.history.com

The legend of Santa Claus can be traced back hundreds of years to a monk named St. Nicholas. It is believed that Nicholas was born sometime around 280 A.D. in Patara, near Myra in modern-day Turkey. ... Over the course of many years, Nicholas's popularity spread and he became known as the protector of children and sailors.

Santa Claus—otherwise known as Saint Nicholas or Kris Kringle— has a long history steeped in Christmas traditions. Today, he is thought of mainly as the jolly man in red who brings toys to good girls and boys on Christmas Eve, but his story stretches all the way back to the 3rd century, when Saint Nicholas walked the earth and became the patron saint of children. Find out more about the history of Santa Claus from his earliest origins to the shopping mall Santas of today, and discover how two New Yorkers–Clement Clark Moore and Thomas Nast–were major influences on the Santa Claus millions of children wait for each Christmas Eve.

This was traditionally considered a lucky day to make large purchases or to get married. By the Renaissance, St. Nicholas was the most popular saint in Europe. Even after the Protestant Reformation, when the veneration of saints began to be discouraged, St. Nicholas maintained a positive reputation, especially in Holland.

So why does Santa Claus wear red?

Prior to Nast's work, Santa's outfit was tan

in color, and it was he that changed it to red,

although he also drew Santa in a green suit

. ... The Coca-Cola Company itself has attributed the red color of the suit to Nast's earlier work. Prior to the Coca-Cola advertising, the image of Santa was in a state of flux.

So there you have it, a brief telling to the story and legendary story story of the the jolly Santa Claus.