At the end of the Game of Thrones season 4 episode "Oathkeeper," an undead White Walker carries off a human child and brings it to its boss, who touches the baby's cheek and transforms it into a snow zombie.
Pictured: a horny old guy turning a child.
That scene actually caused quite a bit of stir in the Game of Th-sorry, A Song of Ice and Fire fandom, because it doesn't appear anywhere in the books. Of course many things in the show aren't found in the books, like Podrick's magical cock, but this scene is different as it answers a lot of important questions about the White Walkers. For example, it tells us that the creatures used to be humans. But where this gets into spoiler territory involves what was probably a simple screw-up on the part of some HBO employee.
Some Reddit users caught an HBO synopsis (that was later deleted) that identified the horned White Walker as "the Night's King." Even if you haven't read the books, you may still know who that is if you've watch the season 2 DVD extra titled "The Night's Watch History." The extra tells of a legend about the 13th commander of the Night's Watch, the guys tasked with killing White Walkers, who failed spectacularly at his job by falling in love with a female Walker, losing his soul in the process, going crazy, and declaring himself ... "Night's King." That's right, the boss of the White Walkers used to be a "crow," which technically makes him Jon Snow's "brother."
*Cue soap opera music*