The appearance of yet another mystical race of people called "The Children" explained the title for the season 4 finale of "Game of Thrones."
Brandon Stark along with his friends Meera and Jojen Reed and his aid Hodor and direworlf, Summer, have found themselves far north beyond the Wall through the guidance of a three-eyed-raven that Bran sees in his dreams.
Once the group come upon a lone weirwood tree in the middle of the snowy landscape, Jojen announces that they have reached their destination. Things did not go well from there as they were swiftly attacked by a group of skeletal creatures that were emerging from beneath the snow.
This is not the first encounter by any of our characters and zombie-like creatures. The ones that attacked Jon Snow and Jeor Mormont in season 1, were practically zombies, the risen bodies of their dead brothers of the Night's Watch.
Since then, all dead bodies have been burnt to prevent them rising again.
What are wights?
Wights are dead men or creatures that are raised by the White Walkers from the dead and are made to do their bidding. It is unclear if the dead must have been killed by the Others for this to happen but all the wildlings burn their dead regardless of manner of death for fear of them rising up again.
What do they look like?
The ones that attacked Castle Black at the beginning of the series and the ones that attacked Brand and company in season 4 are all wights. They look decidedly different with the early ones looking life-like and Bran's wights looking almost completely rotten because the appearance of wights would depend upon the time they were raised from the dead. The ones that attacked Bran had been dead longer and had decayed before they were raised from the dead.
What are their characteristics?
Wights, being dead, feel no fear or pain. This is why they will continue fighting even after several parts are severed as seen in the finale with one stabbing Jojen even while it lay in pieces on the ground. This makes them dangerous and difficult to kill.
Jon Snow and his brothers were able to kill wights through fire which they discovered only by accident. In the season finale, the children used fireballs to defend Brand and his group from the wights that were attacking them.
While they vary in appearance depending on the state the bodies where in upon resurrection, the common characteristics among wights are their bright blue eyes exactly like the ones of White Walkers. They also have blackened outer extremities where the congealed blood has pooled upon their death. A wight is truly killed only once the blue goes out of their eyes.
What to expect in coming seasons
As the battle for the Iron Throne in Westeros Wages on, Stannis and his army are assisting the Night's Watch and the wildlings in their fight against what they feel is the real enemy, The White Walkers and their wights. As the winter fast approaches and the impending danger looms, the appearance of more wights can be expected in coming seasons to pose an even bigger threat to Westeros than any of them could imagine.