Like so many things, there is a vast difference between the Night King of the series and the Night King in the books thus far, with two novels still scheduled for release from George R. R. Martin. In the books, the Others are mentioned very little, and as for the Night King, he is yet to have a proper book counterpart.
the Night’s King was Otherized: Unfortunately, readers are still in some way riveted by the idea of a character being “turned” into a show-like Night King, despite there not even being evidence that the historical Night’s King was ever Otherized. Its roots lie in the mystery on who or what are the Others and how are they “born” or
A subset of the Great Other theory states that the Night King is looking to free the Night Queen, a figure with whom Bran the Builder, the Night’s Watch, and the book version of the Night King
The Night King knows his enemies better than they know him. Plus, he knows who they are and where they live. The Last Hearth was always in grave danger of the White Walkers,
There could be multiple as the winter has marched south many times in past and was pushed backwards by humans and the COTF, besides the particular night king shown in the cave art of dragon stone ( Of Game of thrones) had beard but the night king of the show didn't. I'm not completely on boards with this theory but it's not entirely unlikely. . 282 331 234 306 390 96 75 498

is the night king in the books