Fairly recently — and Coca-Cola is at least partly to blame. St. Nick's signature red suit, in particular, became a recognizable part of the wardrobe sometime in 1931, when artist Haddon Sundblom illustrated Santa as a jovial, rosy-cheeked Coke-drinker for a widely circulated magazine ad. The soda giant was trying to convince consumers that Coca-Cola wasn't just a warm weather thing. Sundblom was likely inspired by the work of cartoonist Thomas Nast, who in the 1890s depicted Santa with a big warm belly. Nearly a century before that, early American writer Washington Irving (The Legend of Sleepy Hollow, Rip Van Winkle) was one of the first to balloon Santa's waistline: In an 1809 book, he switched skinny St. Nicholas and his episcopal robes for a fat elf in traditional Dutch garb. And yes, he looked terrifying.