In stories, giants are outsized men who live in huge castles, carried huge swords, and walk in boots that a boy could hide in (III: 166)
Giants are more bearlike than human, and as wooly as the mammoths they ride (III: 166)
Giants are perhaps ten feet tall, or twelve, but no more than fourteen feet. Their sloping chests might pass for those of men, but their arms hang too low and their lower torsos look to be half again as wide as their upper torso. Their legs are shorter than their arms, but very thick. They wear no boots at all, for their feet are broad splayed things that are hard and horny and black (III: 166)
Neckless, the huge heavy heads of giants thrust forward from between their shoulder blades, and their faces are squashed and brutal. They have tiny rats' eyes almost lost within the folds of horny flesh, but they snuffle constantly, smelling as much as they saw (III: 166, 167)
The hair of the giants cover them in shaggy pelts, thick below the waist and sparser above (III: 167)
The giants use clubs as weapons, most simply being the limbs of dead trees. A few have stone balls lashed to the ends to make colossal mauls, and some have huge stone axes (III: 167, 720)
Older giants have fur gone grey and streaked with white (III: 167)
Giants have huge square teeth (III: 167)
A giant's laugh is half belch and half rumble (III: 167)
The giants have no kings (III: 167)
Giant names are very odd. For example: Mag Mar Tun Doh Weg, which may mean Mag the Mighty (III: 167)
Giants have bad eyes (III: 167)
The wildlings have a song called "The Last of the Giants", which needs a deep voice to be done properly. It's a sad song bemoaning how men have come into the land to hunt the giants from their stone halls, with dogs and fire and sharp spears, and saying that because of them all the giants shall be gone (III: 175, 176)
There are hundreds of giants remaining, but there were once many more. Men killed them (III: 175)
In legend, Brandon the Builder was said to have had the help of giants in raising Winterfell (III: 461)
Giants are hugely strong. One alone is able to wrench great doors off of their hinges, twist off the heads of men with their bare hands even after taking many wounds, and wrench the bars of an iron gate apart (III: 723, 724)