In the Season 4 finale of Game of Thrones Bran and his group meet a child of the forest. Watch the video below to see how the children of the forest look was created.
The children were the first known inhabitants of Westeros, settling long before the first men crossed a land bridge from Essos. They have not been seen in Westeros for thousands of years. According to lore, they are small and magical creatures, and carved the faces in the Weirwood trees that honor their gods.
This video and others behind the scenes special features are available on the Game of Thrones Season 4 Blu-ray.