Short answers, pulled from the story.
The historical figure who became Santa Claus was Nicholas of Myra, a Greek Christian bishop who served in the region of Lycia within the Roman Empire during the 4th century. He is remembered for throwing bags of gold through a window to help three impoverished daughters avoid prostitution. His legacy as a devout religious figure established the core narrative of the modern gift-giver.
The poem A Visit from St. Nicholas was published on the 23rd of December 1823 in the Troy, New York Sentinel. This text introduced the concept of a sleigh pulled by flying reindeer and described a chubby old elf with a round belly. The poem named eight specific reindeer including Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Dunder, and Blixem.
The German-born American cartoonist Thomas Nast created the iconic image of Santa Claus as a portly, white-bearded man in a red coat with white fur trim. His illustration for the 3rd of January 1863 issue of Harper's Weekly depicted Santa dressed in an American flag and included a puppet with the name Jeff written on it. Nast further cemented the mythos by creating the story that Santa lives at the North Pole, a concept that became well known by the 1870s.
Canada granted Santa Claus citizenship in 2008 when Jason Kenney, the Minister of Citizenship, Immigration and Multiculturalism, formally awarded him the status. The postal code H0H 0H0 assigned to the North Pole by Canada Post is a reference to Santa's laugh, Ho ho ho. Canada Post replies to over 1.5 million letters annually in more than 30 languages as of 2015.
Some Christian denominations opposed the figure of Santa Claus because they viewed the tradition as a deceit or falsehood that undermined parental trustworthiness. Mary Baker Eddy, the founder of the Christian Science movement, wrote that children should not be taught that Santa Claus has aught to do with the Christmas pastime. In 1958, Reverend Paul Nedergaard declared Santa a heathen goblin after his image was used on an annual Christmas stamp for a Danish children's welfare organization.
The Guinness World Record for the largest gathering of Santa Clauses is held by Thrissur, Kerala, India. On the 27th of December 2014, 18,112 Santas gathered to overtake the previous record. This event demonstrated the figure's ability to transcend national boundaries and become a universal symbol of holiday cheer.